I need help with a power electronics technical paper study question. **QUESTION*

Question

I need help with a power electronics technical paper study question.

**QUESTION**

II. PRINCIPLE OF SPACE VECTOR PWM The circuit model of a typical three-phase voltage source PWM inverter is shown in Figure 1. Si to S6 are the six power switches that shape the output voltage, which are controlled by the switching variables a, a b, b and c, c When an upper MOSFET is switched on, i.e., when a, b or c is i, the corresponding lower MOSFET is switched off, i e. the corresponding a b or c is 0. Therefore, the on and off tates of the upper MOSFET Si, S3 and S5 can be used to determine the output voltage [15]. Va Fig. l 3 Phase PWM inverter circuit for IDH The relationship between the switching variable vector Da, b, cl' and the line-to-line voltage vector Mab, Vbo, Vea. is given by eq. 1 in the following: 1 0 a ab Dc 0 (1) Also, the relationship between the switching variable vec- tor a, b,clt and the phase voltage vector [Vo bn, Venl" can be expressed below. DC (2) bn, 1 -1 2 c As illustrated in Figure 1, there are eight possible combi- nations of on and off pattems for the three upper power switches. The on and off states of the lower power devices are opposite to the upper one and so are easily determined once the states of the upper power MosFET's are determined. According to eq. 1 and 2, the eight switching vectors, output line to neutral voltage (phase voltage), and output line-to-line voltages in terms of DC-link Vdc, are given in Table I and

Explanation / Answer

Ts is sample time. Here the voltage is sampled by a time Ts so that we can use the same voltage function Vt in discrete form. The reason we write in discrete form is to calculate the value of Vt anytime easy and can be processed in computer analysis by multiplexing it.

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