US 11,863,098 B2
Multi-level inverter
Thomas Schafroth, Ipsach (CH); Peter Schlienger, Auenstein (CH); and Nick Beeli, Attalens (CH)
Assigned to BorgWarner Engineering Services Switzerland AG, Brügg (CH)
Appl. No. 17/276,640
Filed by BorgWarner Engineering Services Switzerland AG, Brügg (CH)
PCT Filed Sep. 16, 2019, PCT No. PCT/EP2019/074665
§ 371(c)(1), (2) Date Mar. 16, 2021,
PCT Pub. No. WO2020/058171, PCT Pub. Date Mar. 26, 2020.
Claims priority of application No. 18195287 (EP), filed on Sep. 18, 2018.
Prior Publication US 2023/0075792 A1, Mar. 9, 2023
Int. Cl. H02P 1/00 (2006.01); H02P 27/14 (2006.01); H02M 1/12 (2006.01); H02M 7/487 (2007.01); H02M 7/5395 (2006.01)
CPC H02P 27/14 (2013.01) [H02M 1/12 (2013.01); H02M 7/487 (2013.01); H02M 7/5395 (2013.01)] 14 Claims
OG exemplary drawing
 
1. Method of controlling a multi-level inverter having inputs connected to a drive unit controlling the inverter and an output connected to a load, the multi-level inverter capable of generating a PWM voltage signal having three or more modulation levels, the inverter powered by a voltage supply and comprising at least one neutral point, the method comprising operating the multi-level inverter in a standard modulation pattern having three or more modulation levels when one or more parameters representative of neutral point stability each have a value within a first range indicative of a high neutral point stability, and operating the multi-level inverter with a two-level modulation pattern when said one or more parameters representative of neutral point stability each have a value within a second range indicative of a low neutral point stability, the first range separated from the second range by a threshold value, wherein said threshold values of parameters representative of low neutral point stability include any one or more of:
 
ωmin Minimum motor stator Threshold value having a value
 
 frequency between 0 to 40% of nominal
 
 
 speed;
εnp_max Allowed deviation of Threshold value having a value
 
 neutral point voltage between 0 to 50 [%];
 
 in %
 
PFmin Motor minimum power Threshold value having a value
 
 factor between 0 to 0.7 [−];
Iph_min Motor minimum phase Threshold value having a
 
 current predetermined value depending on
 
 
 the characteristics of the motor [A];
fpwm_min Minimum PWM Threshold value having a value
 
 frequency between 0 to 50 [kHz].