Confusion about the rated voltage of a Permanent magnet synchronous motor.
I’m currently trying to do a motor control experiment and I’m really confused by a term called “rated voltage” from the motor specifications.
The outputs of the inverter are Vao, Vbo, and Vco. The line-to-neutral voltages would be VaN=(1/3)(2*Vao-Vbo-Vco) VbN=(1/3)(2*Vbo-Vao-Vco) VcN=(1/3)(2*Vco-Vao-Vbo)
And the line-to-line voltage would be Vab=Vao-Vbo Vbc=Vbo-Vco Vca=Vco-Vao
My question is, when we mean rated voltage of a PMSM. Does this value refer to the RMS value of line-to-line voltage, the RMS value of the line-to-neutral voltage, or simply the DC bus voltage of the inverter? I want to clarify this confusion because I know that to drive a motor, the DC bus voltage for an inverter should be 1.414 times larger than the AC RMS line voltage of the Motor.
Assume that the rated voltage of a PMSM is 24V. If this rated voltage means the RMS value of the line-to-line voltage, then the required DC bus voltage (Vdc) should simply be 1.414*24=34V. If this rated voltage mean the RMS value of the line-to-neutral voltage, for a three-phase PMSM, the line-to-line voltage will be 1.732*24=41.5V. And the required DC bus voltage for the inverter will be 59V. If this rated voltage refer to the DC bus voltage of the inverter, then the DC bus voltage for the inverter will simply be 24V. And the line-to-line voltage of this PMSM under rated condition will be 24/1.414 = 17V.
Can anyone clarify this for me?
@ Bruce Abbott
Based on the datasheet I provided in the comment. I picked the part number DN42040S24-026 and used the following motor specs:
Stator phase resistance: 0.75ohm;
Lds & Lqs: 0.0021H; Flux linkage established by PM: 0.00477564V.s;
I have no idea about calculating the viscous damping based on the datasheet, so I assumed the viscous damping to be 0.0001N.m.s. I tried to simulate the motor’s performance at rated condition in Simulink. I initially supplied the motor with 800/3Hz three phase sinusoidal voltage inputs as (let’s call this group 1)
The motor speed is around -5000rpm and have large amplitude oscillations. But when I change the supply voltage to (let’s call this group 2)
The motor speed reaches a steady-state of -4000rpm. I’m confused here because I think I should have the same speed response with either group. Also, I don’t understand why I get a negative speed response at -4000rpm rather than +4000rpm. I tried to switch the phase sequences of group 2, but I get the same speed response as group 1: -5000rpm with large oscillations. I do not know what the problem is here. Any suggestions? Thank you.