An improved digital controller for three-phase PWM inverter with insulating transformer for double conversion UPS

This paper proposes an improved digital voltage controller adequate for three-phase three-leg PWM inverters with an isolator transformer used in double-conversion UPS. The proposed controller is derived from the internal model principle using a state-variable approach in αβ frame. By this control strategy it is possible to obtain a high performance in steady-state. In addition, with the selected internal model, the DC components are not amplified avoiding in this case the output transformer saturation. With this approach it is possible to obtain output voltages with reduced total harmonic distortion (THD) and a good transient performance for linear and non-linear load steps, that compliant whit the international Standard IEC 62040-3. In order to validate the proposed control strategy and to demonstrate the steady-state and transient performance, experimental results are obtained in a 10 kVA space vector modulated three-phase inverter, fully controlled by a DSP TMS320F243.

[1]  W. Wonham,et al.  Synthesis of multivariable regulators: The internal model principle , 1974 .

[2]  Wilhelm Sölter.  A new international UPS classification by IEC 62040-3: Method of specifying the performance and test requirements: First edition 1999-03 / revised and translated 2001-11 , 2002 .

[3]  Fernando Botterón,et al.  A digital controller for single-phase UPS inverters to reduce the output DC component , 2004, 2004 IEEE 35th Annual Power Electronics Specialists Conference (IEEE Cat. No.04CH37551).

[4]  Masayoshi Tomizuka,et al.  Analysis and Synthesis of Discrete-Time Repetitive Controllers , 1989 .

[5]  Prasad N. Enjeti,et al.  DSP control of high-power UPS systems feeding nonlinear loads , 1996, IEEE Trans. Ind. Electron..

[6]  Atsuo Kawamura,et al.  Waveform compensation of PWM inverter with cyclic fluctuating loads , 1988 .

[7]  Masayoshi Tomizuka,et al.  Zero Phase Error Tracking Algorithm for Digital Control , 1987 .

[8]  Humberto Pinheiro,et al.  Comparison of digital control techniques with repetitive integral action for low cost PWM inverters , 2003 .

[9]  H. Ohshima,et al.  Large capacity 3-phase UPS with IGBT PWM inverter , 1991, PESC '91 Record 22nd Annual IEEE Power Electronics Specialists Conference.

[10]  A. Kusko,et al.  Output impedance of PWM UPS inverter-feedback vs. filters , 1990, Conference Record of the 1990 IEEE Industry Applications Society Annual Meeting.

[11]  Li Peng,et al.  The control technique of three-phase voltage-source inverter output waveform based on internal model theory , 2003, IECON'03. 29th Annual Conference of the IEEE Industrial Electronics Society (IEEE Cat. No.03CH37468).

[12]  Emerson Giovani Carati,et al.  A robust high performance three-phase uninterruptible power supply , 2000, Proceedings of the 2000. IEEE International Conference on Control Applications. Conference Proceedings (Cat. No.00CH37162).

[13]  Frede Blaabjerg,et al.  A new space-vector-based control method for UPS systems powering nonlinear and unbalanced loads , 2001 .

[14]  Danwei Wang,et al.  Digital repetitive learning controller for three-phase CVCF PWM inverter , 2001, IEEE Trans. Ind. Electron..

[15]  Paolo Mattavelli,et al.  Synchronous-frame harmonic control for high-performance AC power supplies , 2001 .

[16]  Bruce A. Francis,et al.  The internal model principle of control theory , 1976, Autom..

[17]  H.L. Hey,et al.  A new discrete-time voltage controller based on the internal model principle for three-phase voltage source PWM inverters with /spl Delta/Y output transformer , 2004, 2004 IEEE 35th Annual Power Electronics Specialists Conference (IEEE Cat. No.04CH37551).

[18]  Fernando Botterón,et al.  Digital voltage and current controllers for three-phase PWM inverter for UPS applications , 2001, Conference Record of the 2001 IEEE Industry Applications Conference. 36th IAS Annual Meeting (Cat. No.01CH37248).

[19]  Masayoshi Tomizuka,et al.  Steady-State and Stochastic Performance of a Modified Discrete-Time Prototype Repetitive Controller , 1990 .

[20]  Aleksandar M. Stankovic,et al.  Dissipativity-based adaptive and robust control of UPS in unbalanced operation , 2001 .