Analysis of PWM Voltage Detection Delay for Current Source Type Electric Motor Emulator

This paper focuses on input voltage detection for an electric motor emulator (EME), which imitates various motor operations accurately. The EME has to detect the PWM voltage of an inverter under test (IUT) as the input voltage of the EME. The delay in the PWM voltage detection reduces the emulation accuracy. This paper reveals the relationship between the cutoff frequency of a low-pass filter (LPF) for voltage detection and the current control bandwidth of both the IUT and the EME. The analysis result mentions that a low cutoff frequency, such as 1 kHz, is acceptable under the current control bandwidth of 100 Hz in the IUT. In addition, the cutoff frequency of the LPF should be set to a frequency larger than eight times the current control bandwidth of the IUT to keep the transient response in any conditions. Furthermore, it is verified that the phase lead compensation keeps the current response when the cutoff frequency and the current control bandwidth of the IUT are close.