Hardware » History » Version 10
Luiz Fernando Lavado Villa, 2019-02-28 14:48
1 | 1 | Luiz Fernando Lavado Villa | h1. Hardware |
---|---|---|---|
2 | 2 | Luiz Fernando Lavado Villa | |
3 | 4 | Luiz Fernando Lavado Villa | {{>toc}} |
4 | |||
5 | 2 | Luiz Fernando Lavado Villa | The hardware of the single-phase project consists of a 10cm by 10cm printed circuit board that hosts 5 electronics blocks. |
6 | 3 | Luiz Fernando Lavado Villa | These blocks all fulfill functions which are necessary to the proper operation of any power electronics converter. |
7 | Figure 1 illustrates these blocks. |
||
8 | 1 | Luiz Fernando Lavado Villa | |
9 | 9 | Luiz Fernando Lavado Villa | p=. {{thumbnail(theory_power_converter_1.png, size=350, title=General overview of a power electronics converter)}} |
10 | _Figure 1 - General overview of a power electronics converter_ |
||
11 | 1 | Luiz Fernando Lavado Villa | |
12 | 4 | Luiz Fernando Lavado Villa | Each block is explained in detail in the sections below. |
13 | 1 | Luiz Fernando Lavado Villa | |
14 | 4 | Luiz Fernando Lavado Villa | h2. Power Block |
15 | 1 | Luiz Fernando Lavado Villa | |
16 | 9 | Luiz Fernando Lavado Villa | To better explain the Power Block, this page splits its presentation in theory and practice. |
17 | |||
18 | h3. Theory |
||
19 | |||
20 | 5 | Luiz Fernando Lavado Villa | The Power Block is the part that manages input/output power within the board. |
21 | It consists of a single inverter leg, as illustrated in the figure below. |
||
22 | |||
23 | |||
24 | 1 | Luiz Fernando Lavado Villa | p=. {{thumbnail(single_phase_topology.png, size=350, title=The power topology of the single-phase board)}} |
25 | 9 | Luiz Fernando Lavado Villa | _Figure 2 - The power topology of the single-phase board_ |
26 | 1 | Luiz Fernando Lavado Villa | |
27 | 9 | Luiz Fernando Lavado Villa | Figure 2 shows a Vlow, VHigh, T1, T2, D1, D2 and L. |
28 | Vlow is the low-side voltage, VHigh is the high-side voltage, T1 and T2 are two transistors, D1 and D2 are two diodes and L is an inductor. |
||
29 | 1 | Luiz Fernando Lavado Villa | |
30 | 9 | Luiz Fernando Lavado Villa | |
31 | This topology is current bi-directional. |
||
32 | This means that its input can be either on the high-side or on the low-side. |
||
33 | If the input is on the high-side, the circuit acts as a buck or step-down converter. |
||
34 | If the input is on the low-side, the circuit acts as a boost or step-up converter. |
||
35 | |||
36 | |||
37 | 6 | Luiz Fernando Lavado Villa | This topology allows the control of the current in the inductor L by controlling its charge and discharge using the switches. |
38 | The figure below shows the switching and the current flow within the inductor. |
||
39 | |||
40 | 1 | Luiz Fernando Lavado Villa | p=. {{thumbnail(states_converter_1.png, size=700, title=Current flow during switching)}} |
41 | 9 | Luiz Fernando Lavado Villa | _Figure 3 - The power topology of the single-phase board_ |
42 | 8 | Luiz Fernando Lavado Villa | |
43 | The switching leads to an average current flow between its input and output as shown in the image below. |
||
44 | |||
45 | 1 | Luiz Fernando Lavado Villa | p=. {{thumbnail(switching_states_1.png, size=700, title=Current flow during switching)}} |
46 | 9 | Luiz Fernando Lavado Villa | _Figure 4 - Left: average current in the inductor increases_ |
47 | _Center: average current in the inductor stable_ |
||
48 | _Right: average current in the inductor decreases_ |
||
49 | 1 | Luiz Fernando Lavado Villa | |
50 | 9 | Luiz Fernando Lavado Villa | As figure 4 shows, the key to control the current in the power converter is to control the duration of the signal that is sent to the transistors. |
51 | This duration is called *duty cycle* . |
||
52 | A longer duty cycle will lead to a increase in current, while a shorter duty cycle will lead to a decrease in current. |
||
53 | |||
54 | The duty cycle is the single most important control variable in a power converter. |
||
55 | |||
56 | 10 | Luiz Fernando Lavado Villa | The presentation above is, obviously, not complete since there are further phenomena to be taken into account. |
57 | 9 | Luiz Fernando Lavado Villa | The instantaneous rise and fall in current will lead to abrupt variations in voltage at both the high and low sides. |
58 | To filter these variations, power converters are equipped with capacitors in both sides, which effectively provide the instantaneous current needed by the converter. |
||
59 | |||
60 | The relationship between high and low side voltages, high and low side currents, and the duty cycle is given by the equations below. |
||
61 | |||
62 | 1 | Luiz Fernando Lavado Villa | |
63 | 9 | Luiz Fernando Lavado Villa | p=. !http://www.codecogs.com/eq.latex?\dfrac{V_{High}}{V_{Low}}=\dfrac{I_{Low}}{I_{High}}=\dfrac{1}{1-D}! |
64 | 10 | Luiz Fernando Lavado Villa | _Equation 1 - Relation between High and Low variables, and the duty cycle for a Boost Mode operation_ |
65 | 9 | Luiz Fernando Lavado Villa | |
66 | 10 | Luiz Fernando Lavado Villa | p=. !http://www.codecogs.com/eq.latex?\dfrac{V_{High}}{V_{Low}}=\dfrac{I_{Low}}{I_{High}}=\dfrac{1}{D}! [1] |
67 | _Equation 2 - Relation between High and Low variables, and the duty cycle for a Buck Mode operation_ |
||
68 | 1 | Luiz Fernando Lavado Villa | |
69 | 10 | Luiz Fernando Lavado Villa | |
70 | The required condition for these equations to |
||
71 | All the other blocks exist to provide stable operation conditions that |
||
72 | 9 | Luiz Fernando Lavado Villa | |
73 | h3. Practice |
||
74 | 8 | Luiz Fernando Lavado Villa | |
75 | |||
76 | |||
77 | |||
78 | 6 | Luiz Fernando Lavado Villa | |
79 | |||
80 | 5 | Luiz Fernando Lavado Villa | |
81 | |||
82 | 4 | Luiz Fernando Lavado Villa | h2. Measurement Block |
83 | |||
84 | h2. Control Block |
||
85 | |||
86 | h2. Driver Block |
||
87 | |||
88 | h2. Feeder Block |