Control apparatus of AC motor and refrigerating and air conditioning apparatus using same
A technology for AC motors and control devices, applied in AC motor control, motor generator control, electronically commutated motor control, etc., can solve problems such as driving AC motors, DC bus current errors, and inability to achieve high performance
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no. 1 example
[0047] use Figure 1 to Figure 6 The control device of the first embodiment will be described. exist figure 1 Among them, the AC motor 1 outputs torque corresponding to the three-phase AC currents Iu, Iv, and Iw applied from the inverter 2 . The inverter 2 includes switching elements Sup, Sun, Svp, Svn, Swp, and Swn, and applies three-phase AC voltages Vu, Vv, and Vw to the AC motor 1 to supply AC power. The DC power supply 3 applies a DC voltage VDC to the inverter 2 to provide DC power. The DC bus current detector 4 detects the DC bus current IDC of the inverter 2 . The low-pass filter 5 smoothes the detection value of the DC bus current detector 4 . Corrector 6 corrects the amount of attenuation of the detected value by low-pass filter 5 . The inverter control circuit 7 controls the switching elements Sup, Sun, Svp, Svn, Swp, and Swn to be turned on and off. In addition, details of the PWM signal generating section 7a, the vector control section 7b, and the current es...
no. 2 example
[0072] use figure 1 The second embodiment will be described. In addition, descriptions of the same parts as those in the first embodiment are omitted.
[0073] In this example, if figure 1 As shown, the inverter control circuit 7 includes a PWM signal generation unit 7a, a vector control unit 7b, and a current estimation unit 7c. Accordingly, the motor current I1 is estimated, and the vector control of the AC motor 1 is performed. Hereinafter, this will be described in detail.
[0074] Based on the output from the corrector 6, the current estimating section 7c estimates that at image 3 The reactive current Ir and the active current Ia that have been explained in , and estimate the amplitude and phase of the motor current I1. The estimation principle is described below.
[0075] Depend on image 3 It can be seen that the reactive current Ir and the active current Ia are expressed by (Formula 6) and (Formula 7) respectively.
[0076] I r =I 1 sinφ ... (Formula 6)
[...
no. 3 example
[0096] use Figure 7 The third embodiment will be described. In addition, descriptions of the same parts as those in the second embodiment are omitted.
[0097] From (Formula 13) and (Formula 14), we can see that the coefficient Δk r1 , Δk r2 , Δk a1 , Δk a2 depends on figure 2 The voltage phases θv1, θv2, θv3 are shown. Since the voltage phase θv advances as the AC motor 1 is driven, the coefficient Δk is recalculated using (Equation 13), (Equation 14) in each current estimation r1 , Δk r2 , Δk a1 , Δk a2 In the case of , a large computational load is required in the corrector 6 . In addition, in the pre-stored coefficient Δk r1 , Δk r2 , Δk a1 , Δk a2 In the case of , the corrector 6 must have a large-capacity memory that stores all the coefficients.
[0098] Therefore, in this embodiment, the coefficient Δk of the unity (Equation 15) r1 , Δk r2 , Δk a1 , Δk a2 , so that the calculation load or storage capacity of the corrector 6 is reduced.
[0099] In ...
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