Patent ID: 11863098
Assignee: BORGWARNER ENGINEERING SERVICES SWITZERLAND AG
Field: Electrical machinery, apparatus, energy (Electrical engineering)
Classification: CPC H | IPC H

Claim 0:
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].