История изменений

Угу. Вот, например, как раз про это и про фазу 90 градусов.

http://www.stmicroelectronics.com.cn/resource/en/application_note/cd00003975.pdf

только тут почему-то написано even, а на картинке odd. Опечатались.

3.3 HARMONICS AND POWER DRAWN FROM THE MAINS

The low frequency harmonics content generated on the mains strongly depends on the kind of motor control used (phase angle or chopper). For example, a vacuum cleaner operating in phase angle mode at reduced speed (i.e. conduction phase angle at around 90°), produces a very high level of even harmonics (Figure 5.). The harmonics do not represent real or active power, but nevertheless they lead to substantial copper and iron losses. Consequently, the power supplied to the vacuum cleaner for the same mechanical output power is twice as high using phase angle control as it is when the chopping control method is used.

И другие источники про это https://www.st.com/resource/en/application_note/cd00004291.pdf

(а вот тут правильно - odd)

A universal motor operating at reduced speed (i.e firing angle at around 90 degree) produces very high level of odd harmonics. In experiments with a 1500kW vacuum cleaner at 230V/ 50Hz with the same load, harmonic currents were found to be outside the limits when running at reduced power levels from 470W to 1200W. Practical experience shows that 3rd harmonic currents are determined not only by the motor current amplitude, but also by the conduction time.

Угу. Вот, например, как раз про это и про фазу 90 градусов.

http://www.stmicroelectronics.com.cn/resource/en/application_note/cd00003975.pdf

3.3 HARMONICS AND POWER DRAWN FROM THE MAINS

The low frequency harmonics content generated on the mains strongly depends on the kind of motor control used (phase angle or chopper). For example, a vacuum cleaner operating in phase angle mode at reduced speed (i.e. conduction phase angle at around 90°), produces a very high level of even harmonics (Figure 5.). The harmonics do not represent real or active power, but nevertheless they lead to substantial copper and iron losses. Consequently, the power supplied to the vacuum cleaner for the same mechanical output power is twice as high using phase angle control as it is when the chopping control method is used.