Vector control technology is one of the essential technologies for driving a motor efficiently with low power consumption. We explain about the vector engine (VE) that can reduce the software load during vector control.

Let’s get started with an explanation of

a 3-phase motor and its driver.

Let’s get started with an explanation of

a 3-phase motor and its driver.

**Iu + Iv + Iw = 0**

If the currents of 3-phases are assumed to be Iu,Iv and Iw and the currents after 2-phase conversion are assumed to be Iα and Iβ, the result will be

**Iu + Iv + Iw = 0
Iα= Iu
Iβ= (Iu + 2Iv) / √3**

Park conversion

If the currents in the stationary coordinates are assumed to be Iα and Iβ, those in the rotating coordinates are assumed to be Id, and Iq and a rotating angle is assumed to be θ, then, result will be

**Id = Iα・cosθ+ Iβ・sinθ
Iq = －Iα・sinθ+ Iβ・cosθ**

Let's proceed on the assumption that the rotation angle is known.

Reverse Park Conversion

**Vα= Vd・cosθ－Vq・sinθ
Vβ= Vd・sinθ+Vq・cosθ**

Well, the vector control is now in the final stage. The final conversion is space vector modulation.

vector modulation is.

The goal is just around the corner,

but this is the most difficult part.

Now, this V is decomposed into the vector of two axes (100) and (110) when the sector 0 has the voltage vector V.

If the ingredient of (100) sets to t1 and the ingredient of (110) sets to t2, a lower left figure will be obtained.

**u=t1＋t2
v=t2**

First, please note that there is no axis for the vectors (000) and (111) in the figure of six sectors. Since (000) is u=v=w=0, a driver cannot supply current to a motor because the transistors by the side of VDC of a driver are all OFF state. On the other hand, (111) is u=v=w=1. Reversal input is x=y=z=0 at this time. That is, since all of 3 transistors by the side of GND become OFF, the driver cannot supply current either. Therefore, (000) (111) are the operation “which nothing performs toward a motor”. Furthermore, in order to make the waveform inputted into a driver in space vector modulation, a certain fixed cycle T is decided. Although the voltage vector V is rotating with the rotor, the cycle T is very short time and it is considered during this cycle that the voltage vector V is standing still.

Now, the voltage vector V in the sector 0 was decomposed into t1 and t2.

Cycle T is defined as…

**T=t1+t2+t3**

**u=t1+t2+t3/2
v=t2+t3/2
w=t3/2**

motor control appeared, vector control

can be performed easily and efficiently.

[1] The target current values Iqref and Idref and the rotation angle theta of a rotor are set to a vector engine.

⇒ CPU

[2] A value of phase output voltage (pulse width equivalent to the output voltage of U,V, and W) is set to PMD. The conversion start timing of an AD converter is calculated and the timing is set to PMD.

⇒ VE

[3] A PMD circuit outputs the voltage (PWM) given to new U, V, and W, and transmits a conversion start signal to an AD converter.

⇒ PMD

[4] An AD converter transmits an end signal to a vector engine, after ending conversion.

⇒ ADC

[5] An AD translation result is taken in, the feedback current Id and Iq are calculated, and interruption is required of CPU.

⇒ VE

[6] In response to interruption, angle calculation of a rotor and a new current instruction value are calculated by software.

⇒ CPU

- Sine/Cosine calculation
- Current control (PI control)
- Stationary coordinate conversion

- Space vector control
- 2 phase 3 phase conversion
- Rotating coordinate conversion

It is vector engine that performs these six works.

Thus, a vector engine is hardware very convenient to perform vector control.

Quite difficult contents, but if you would like to know

more details about vector control,

refer to a technical book.

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also offers microcontroller seminars. please participate.

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