US 11,784,583 B2
Cascaded pulse width modulation converter control
Mario Schweizer, Rütihof (CH); Tobias Geyer, Ennetbaden (CH); and Ioannis Tsoumas, Zürich (CH)
Assigned to ABB Schweiz AG, Baden (CH)
Appl. No. 17/601,312
Filed by ABB Schweiz AG, Baden (CH)
PCT Filed Mar. 3, 2020, PCT No. PCT/EP2020/055583
§ 371(c)(1), (2) Date Oct. 4, 2021,
PCT Pub. No. WO2020/182548, PCT Pub. Date Sep. 17, 2020.
Claims priority of application No. 19162755 (EP), filed on Mar. 14, 2019.
Prior Publication US 2022/0216803 A1, Jul. 7, 2022
Int. Cl. H02M 7/49 (2007.01); H02M 1/00 (2006.01); H02M 7/487 (2007.01); H02M 7/483 (2007.01)
CPC H02M 7/49 (2013.01) [H02M 1/007 (2021.05); H02M 7/483 (2013.01); H02M 7/487 (2013.01)] 18 Claims
 
7. An electrical converter, comprising:
a main converter for generating a first output voltage and a first converter cell for converting the first output voltage into a second output voltage, the electrical converter comprises a second converter cell for converting the second output voltage into a third output voltage, wherein the first converter cell comprises a first half-bridge for receiving the first output voltage and a second half-bridge for providing the second output voltage; and
a controller, the controller configured to at least instruct the electrical converter to:
receive a reference voltage for the electrical converter;
pulse width modulate the reference voltage with a first modulation frequency for generating a first switching signal for the main converter;
switch the main converter with the first switching signal to generate the first output voltage;
estimate the first output voltage from the first switching signal;
determine a first voltage error by subtracting the estimated first output voltage from the reference voltage;
pulse width modulate the first voltage error with a second modulation frequency, which is higher than the first modulation frequency, for generating a further switching signal for the first converter cell;
switch the first converter cell with the further switching signal to generate the second output voltage;
estimate the second output voltage from the further switching signal, which is a second switching signal;
determine a second voltage error by subtracting the estimated second output voltage from the first voltage error;
pulse width modulate the second voltage error with a third modulation frequency, which is higher than the second modulation frequency, for generating a third switching signal for the second converter cell;
switch the second converter cell with the third switching signal to generate the third output voltage;
generate the second switching signal from the first voltage error, wherein the second switching signal is 0, if the first voltage error is higher than 0, and the second switching signal is 1, if the first voltage error is lower than 0;
switch the first half-bridge with the second switching signal;
pulse width modulate the first voltage error with an upper carrier signal for generating an upper third switching signal and with a lower carrier signal for generating a lower third switching signal, wherein the upper carrier signal sweeps a positive voltage range and the lower carrier signal sweeps a negative voltage range;
select the upper third switching signal, if the first voltage error is higher than 0, and selecting the lower third switching signal, if the first voltage error is lower than 0; and
switch the second half-bridge with the third switching signal for generating the second output voltage.