Control to output dynamic response and extend modulation index range with hybrid selective harmonic current mitigation-PWM and phase-shift PWM for four-quadrant cascaded H-bridge converters
View Patent ↗A hybrid Cascaded H-Bridge (CHB) converter includes a selective harmonic current mitigation pulse width modulation (SHCM-PWM) unit coupled to an input current and providing an output signal SW SHCM , a phase shift pulse width modulation (PSPWM) unit coupled to the input current and providing an output signal SW PS , a modulation selector coupled to the output signal SW SHCM of the SHCM-PWM unit and the output signal SW PS of the PSPWM unit and providing an output signal SW, and a CHB converter coupled to the output signal SW of the modulation selector. The modulation selector can select one of the output signals (SW SHCM and SW PS ) as the output signal SW based on the input current. The hybrid technique is for cascaded multilevel converters which utilizes asymmetric SHCM to mitigate the harmonics generated from PS-PWM to meet harmonic limits with a smaller number of switching transitions and smaller inductance than the conventional PS-PWM technique.
1. A hybrid Cascaded H-Bridge (CHB) converter, comprising:
a selective harmonic current mitigation pulse width modulation (SHCM-PWM) unit coupled to an input current and providing an output signal SW SHCM ;
a phase shift pulse width modulation (PSPWM) unit coupled to the input current and providing an output signal SW PS ; and
a CHB converter selectively coupled to the SHCM-PWM unit and the PSPWM unit,
wherein the CHB converter is coupled to the SHCM-PWM unit under steady state condition and the CHB converter is coupled to the PSPWM unit under dynamic condition; and
wherein the input current includes an active current reference ΔI* in-d and a reactive current reference ΔI* in-q , and the CHB converter is selectively coupled to the SHCM-PWM unit and the PSPWM unit based on the active current reference ΔI* in-d and the reactive current reference.
2. The hybrid CHB converter according to claim 1 , wherein the CHB converter is coupled to the PSPWM unit under transient condition.
3. The hybrid CHB converter according to claim 1 , wherein the CHB converter is selectively coupled to the PSPWM unit in case the input current satisfies the following Formula 1:
|Δ I* in-d |>0 & ω t=k π, until ω t =( k+ 2)π. Formula 1
4. The hybrid CHB converter according to claim 3 , wherein the CHB converter is selectively coupled to the PSPWM unit in case the input current satisfies the following Formula 2:
|Δ I* in-d >0 & ω t=kπ+π/ 2, until ω t =( k+ 2)π. Formula 2
5. The hybrid CHB converter according to claim 4 , wherein the CHB converter is selectively coupled to the SHCM-PWM unit in all cases where the input current does not satisfy either of Formula 1 and Formula 2.
6. The hybrid CHB converter according to claim 1 , further comprising an indirect controller coupled to the input current and providing an output current v ac-CHB2 to the SHCM-PWM unit and the PSPWM unit.
7. A hybrid Cascaded H-Bridge (CHB) converter, comprising:
a selective harmonic current mitigation pulse width modulation (SHCM-PWM) unit coupled to an input current and providing an output signal SW SHCM ;
a phase shift pulse width modulation (PSPWM) unit coupled to the input current and providing an output signal SW PS ;
a modulation selector coupled to the output signal SW SHCM of the SHCM-PWM unit and the output signal SW PS of the PSPWM unit and providing an output signal SW, wherein the input current includes an active current reference ΔI* in-d and a reactive current reference ΔI* in-q , and wherein the modulation selector selects one of the output signal SW SHCM and the output signal SW PS based on the active current reference ΔI* in-d and the reactive current reference ΔI* in-d ; and
a CHB converter coupled to the output signal SW of the modulation selector.
8. The hybrid CHB converter according to claim 7 , wherein the modulation selector is connected to the input current.
9. The hybrid CHB converter according to claim 7 , further comprising an indirect controller coupled to the input current and providing an output current v ac-CHB2 to the SHCM-PWM unit and the PSPWM unit.
10. The hybrid CHB converter according to claim 9 , further comprising a phase lock loop (PLL) coupled to the modulation selector and an output of the CHB converter.
11. The hybrid CHB converter according to claim 7 , wherein the modulation selector selects the output signal SW PS in case the input current satisfies the following Formulas 3 and 4:
Δ I* in-q >0 & ω t=k π, until ω t =( k+ 2)π, Formula 3
Δ I* in-q >0 & ω t=kπ+π/ 2, until ω t =( k+ 2)π. Formula 4
12. The hybrid CHB converter according to claim 11 , the modulation selector selects the output signal SW SHCM in all cases where the input current does not satisfy both Formula 3 and Formula 4.
13. A hybrid Cascaded H-Bridge (CHB) converter, comprising:
an asymmetric selective harmonic current mitigation pulse width modulation (ASHCM-PWM) unit coupled to an input current and providing an output signal SW ASHCM ;
a phase shift pulse width modulation (PSPWM) unit coupled to the input current and providing an output signal SW PS ;
a P-cell H-Bridge coupled to the output signal SW ASHCM of the ASHCM-PWM unit; and
a N-cell H-Bridge coupled to the output signal SW PS of the PSPWM unit.
14. The hybrid CHB converter according to claim 13 , further comprising an indirect controller coupled to the input current and providing an output current to the ASHCM-PWM unit and the PSPWM unit.
15. The hybrid CHB converter according to claim 14 , wherein the input current includes an active current reference ΔI* in-1-d and a reactive current reference ΔI* in-1-q , and the P-cell inputs the output signal SW ASHCM active current reference ΔI* in-1-d and the N-cell inputs the output signal SW PS based on the reactive current reference ΔI* in-1-q .
16. The hybrid CHB converter according to claim 13 , wherein the P-cell H-Bridge is coupled to the ASHCM-PWM unit under steady state condition and the N-cell H-Bridge is coupled to the PSPWM unit under dynamic condition.
17. The hybrid CHB converter according to claim 15 , wherein the active current reference ΔI* in-1-d and the reactive current reference ΔI* in-1-q are limited to change once in each half period.
18. The hybrid CHB converter according to claim 14 , wherein the P-cell H-Bridge and the N-cell H-Bridge are connected to a coupling inductance.