Design of excitation current estimation algorithm for wireless excitation system of electrically excited motors based on S-N resonant topology

Beibei Song; Shuai Ren; Shumei Cui; Shuai Dong; Shiwei Shi; Shaoshuan Qi; Beibei Song; Shuai Ren; Shumei Cui; Shuai Dong; Shiwei Shi; Shaoshuan Qi

doi:10.48130/wpt-0025-0034

Figures (15) Tables (3)

Figure 1.
Effects of strong coupling on system performance. (a) High harmonic content. (b) Discontinuous current mode.
Figure 2.
Exploded diagram of S-N topology wireless excitation system.
Figure 3.
Wireless excitation systems with S-N topology based on different equivalent models. (a) Based on mutual inductance model. (b) Based on single leakage inductance model.
Figure 4.
Voltage and current waveforms of primary and secondary sides.
Figure 5.
Control block diagram of wireless excitation system and the principle block diagram of five different estimation approaches. (a) Control block diagram of wireless excitation system. (b) Principle block diagram of approach 1. (c) Principle block diagram of approach 2. (d) Principle block diagram of approach 3. (e) Principle block diagram of approach 4. (f) Principle block diagram of approach 5.
Figure 6.
The value of power angle θ obtained by different methods.
Figure 7.
Sampling waveforms of u₁ and i₁ at different sampling frequencies. (a) 400 kHz (five times f). (b) 800 kHz (ten times f).
Figure 8.
The value of cosθ and tanθ obtained by different method. (a) The value of cosθ obtained by different methods. (b) The value of tanθ obtained by different methods.
Figure 9.
Estimation results of five different estimation approaches.
Figure 10.
Comparison radar chart of five different estimation approaches.
Figure 11.
Block diagram of excitation-current calculation.
Figure 12.
Estimation error under different parameter-normalization variations (0.90–1.10). (a) Self-inductance L_P and L_S. (b) Resonant capacitance C_P and mutual inductance M. (c) Current and voltage sensor noise. (d) Operating frequency f.
Figure 13.
Experimental platform for the S-N compensated wireless excitation system.
Figure 14.
Waveform diagrams of voltage u₁, current i₁ and the MOSFET ZVS soft switching. (a) Waveform diagrams of voltage u₁ and current i₁. (b) Waveform of MOSFET ZVS soft switching.
Figure 15.
The waveform of actual excitation current vs target value variation.

Approach	Methods to obtain θ	Equation	Sampling targets
Approach 1	Calculation method	Eq. (13)	U_dc I_{1_rms}
Approach 2	Calculation method	Eq. (12)	U_dc I_{1_rms}
Approach 3	Calculation method	Eq. (13)	\|u₁\| I_{1_rms}
Approach 4	Sampling method	Eq. (12)	U_dc u₁ i₁
Approach 5	Sampling method	Eq. (13)	I_{1_rms} u₁ i₁

Table 1.

Description of five estimation approaches.

Components Parameters Components Parameters

U_dc 24 V M 32.266 μH
f 80 kHz C_P 438.74 nF
L_P 33.756 μH R_f 4.3 Ω
L_S 42.09 μH L_f 180 mH

Table 2.
Parameters of S-N wireless excitation system.
Target value Steady-state mean value Error

1 A 0.976 A 2.4%

2 A 2.008 A 0.4%

3 A 3.004 A 0.13%

4 A 4.006 A 0.15%

Table 3.
Error analysis of the current estimation algorithm.

Components	Parameters	Components	Parameters
U_dc	24 V	M	32.266 μH
f	80 kHz	C_P	438.74 nF
L_P	33.756 μH	R_f	4.3 Ω
L_S	42.09 μH	L_f	180 mH

Target value	Steady-state mean value	Error
1 A	0.976 A	2.4%
2 A	2.008 A	0.4%
3 A	3.004 A	0.13%
4 A	4.006 A	0.15%