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| en:iot-open:hardware2:powering:converters [2023/11/13 16:39] – [Power Conversion] pczekalski | en:iot-open:hardware2:powering:converters [2023/11/23 11:45] (current) – pczekalski |
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| ====== Power converters for IoT systems ====== | ====== Converters for IoT Powering ====== |
| | {{:en:iot-open:czapka_b.png?50| General audience classification icon }}{{:en:iot-open:czapka_e.png?50| General audience classification icon }}\\ |
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| | ===== Power Conversion ===== |
| ==== Power Conversion ==== | |
| Power sources tend to provide energy in a form that is not straightforwardly acceptable to IoT devices.\\ | Power sources tend to provide energy in a form that is not straightforwardly acceptable to IoT devices.\\ |
| Wall sockets provide relatively high voltage alternating current (AC) that needs to be lowered and converted into DC, also stabilised as required by MCU, which is fragile for voltage variations. Common conversion flow for AC sources is present in figure {{ref>powerconversions1}}. DC power sources (such as batteries) also require voltage conversion and stabilisation. The flow is present in figure {{ref>powerconversions2}}. | Wall sockets provide relatively high voltage alternating current (AC) that needs to be lowered and converted into DC, also stabilised as required by MCU, which is fragile for voltage variations. Common conversion flow for AC sources is present in figure {{ref>powerconversions1}}. DC power sources (such as batteries) also require voltage conversion and stabilisation. The flow is present in figure {{ref>powerconversions2}}. |
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| <figure powerconversions1> | <figure powerconversions1> |
| {{ :en:iot-open:hardware2:powering:power_conversions.png?500 |}} | {{ :en:iot-open:hardware2:powering:power_conversions.png?500 | AC power source conversion flow}} |
| <caption>AC power source conversion flow</caption> | <caption>AC power source conversion flow</caption> |
| </figure> | </figure> |
| |
| <figure powerconversions2> | <figure powerconversions2> |
| {{ :en:iot-open:hardware2:powering:power_conversions2.png?300 |}} | {{ :en:iot-open:hardware2:powering:power_conversions2.png?250 | DC power source conversion flow}} |
| <caption>DC power source conversion flow</caption> | <caption>DC power source conversion flow</caption> |
| </figure> | </figure> |
| **AC-to-AC**\\ | **AC-to-AC**\\ |
| AC-to-AC conversion is used whenever a high-voltage source is available and is required to lower it, typically somewhere between 12V and 5V.\\ | AC-to-AC conversion is used whenever a high-voltage source is available and is required to lower it, typically somewhere between 12V and 5V.\\ |
| Historically, AC-to-AC conversion was implemented using a transformer (symbol in figure {{ref>transformer1}}). This technique has serious drawbacks: | Historically, AC-to-AC conversion was implemented using a transformer (symbol in figure {{ref>transformer1}}). |
| | This technique has serious drawbacks: |
| * transformer-based converters are heavy as they use copper coils and steel cores (sample transformer in figure {{ref>transformer2}}), | * transformer-based converters are heavy as they use copper coils and steel cores (sample transformer in figure {{ref>transformer2}}), |
| * the conversion rate is fixed, thus requiring different transformers in the countries with different socket voltages, | * the conversion rate is fixed, thus requiring different transformers in the countries with different socket voltages, |
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| <figure transformer1> | <figure transformer1> |
| {{ :en:iot-open:hardware2:powering:transformer.png?100 |}} | {{ :en:iot-open:hardware2:powering:transformer.png?100 | Transformer symbol}} |
| <caption>Transformer symbol</caption> | <caption>Transformer symbol</caption> |
| </figure> | </figure> |
| |
| <figure transformer2> | <figure transformer2> |
| {{ :en:iot-open:hardware2:powering:transformer.jpg?200 |}} | {{ :en:iot-open:hardware2:powering:transformer.jpg?200 | Sample high to low voltage transformer}} |
| <caption>Sample high to low voltage transformer</caption> | <caption>Sample high to low voltage transformer</caption> |
| </figure> | </figure> |
| |
| **AC-to-DC**\\ | **AC-to-DC**\\ |
| In general, IoT devices use DC to power MCUs and peripherals. A classical AC-to-DC conversion involves a Graetz's bridge with 4 diodes, currently implemented commonly in a single enclosure as in figure {{ref>graetz2}}. | In general, IoT devices use DC to power MCUs and peripherals. A classical AC-to-DC conversion involves a Graetz's bridge with 4 diodes (schematic in figure {{ref>graetz1}}), currently implemented commonly in a single enclosure as in figure {{ref>graetz2}}. |
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| <figure graetz1> | <figure graetz1> |
| {{ :en:iot-open:hardware2:powering:graetz.png?100 |}} | {{ :en:iot-open:hardware2:powering:graetz.png?100 | Graetz bridge}} |
| <caption>Graetz bridge</caption> | <caption>Graetz bridge</caption> |
| </figure> | </figure> |
| |
| <figure graetz2> | <figure graetz2> |
| {{ :en:iot-open:hardware2:powering:graetz.jpg?100 |}} | {{ :en:iot-open:hardware2:powering:graetz.jpg?100 | Graetz bridge in single enclosure}} |
| <caption>Graetz bridge in single enclosure</caption> | <caption>Graetz bridge in single enclosure</caption> |
| </figure> | </figure> |
| SMPS is used to integrate all necessary functions (including voltage stabiliser) in a single device, e.g. in figure {{ref>acdc1}}. | SMPS is used to integrate all necessary functions (including voltage stabiliser) in a single device, e.g. in figure {{ref>acdc1}}. |
| <figure acdc1> | <figure acdc1> |
| {{ :en:iot-open:hardware2:powering:20231017_172145.jpg?400 |}} | {{ :en:iot-open:hardware2:powering:20231017_172145.jpg?280 | Sample AC to DC converter with voltage stabilised output}} |
| <caption>Sample AC to DC converter with voltage stabilised output</caption> | <caption>Sample AC to DC converter with voltage stabilised output</caption> |
| </figure> | </figure> |
| |
| **Filtering**\\ | **Filtering**\\ |
| Proper filtering of the current interferences is essential to ensure stable MCU operation. Even when using good quality power sources, nearby communication wires, power wires, and electromagnetic fields generated by actuators can cause serious interference voltage rise and drop. For this reason, the use of capacitors is essential. A rule of thumb is to add a large capacity (e.g. 1000uF) capacitor on the power bus and 100nF capacitors close to the IoT device's MCU and other sensitive components. It may be specific to the device, so unstable work may require analysis of the power bus interferences regarding their frequency and amount. | Proper filtering of the current interferences is essential to ensure stable MCU operation. Even when using good quality power sources, nearby communication wires, power wires, and electromagnetic fields generated by actuators can cause severe interference voltage rise and drop. For this reason, the use of capacitors is essential. A rule of thumb is to add a large capacity (e.g. 1000uF) capacitor on the power bus and 100nF capacitors close to the IoT device's MCU and other sensitive components. It may be specific to the device so unstable work may require analysis of the power bus interferences regarding their frequency and amount. |
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| **DC-to-DC and voltage stabilisation**\\ | **DC-to-DC and voltage stabilisation**\\ |
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| <figure 7805> | <figure 7805> |
| {{ :en:iot-open:hardware2:powering:lm7805-5v-1a-linear-regulator.png?200 |}} | {{ :en:iot-open:hardware2:powering:lm7805-5v-1a-linear-regulator.png?100 | Linear voltage regulator}} |
| <caption>Linear voltage regulator</caption> | <caption>Linear voltage regulator</caption> |
| </figure> | </figure> |
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| <figure 7805_2> | <figure 7805_2> |
| {{ :en:iot-open:hardware2:powering:7805.png?200 |}} | {{ :en:iot-open:hardware2:powering:7805.png?200 | Linear voltage regulator application circuit}} |
| <caption>Linear voltage regulator</caption> | <caption>Linear voltage regulator application circuit</caption> |
| </figure> | </figure> |
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| <figure dcdcswitching1> | <figure dcdcswitching1> |
| {{ :en:iot-open:hardware2:powering:20231017_171951.jpg?200 |}} | {{ :en:iot-open:hardware2:powering:20231017_171951.jpg?200 | Fixed voltage step down converter module}} |
| <caption>Fixed voltage step down converter module</caption> | <caption>Fixed voltage step down converter module</caption> |
| </figure> | </figure> |
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| <figure dcdcswitching2> | <figure dcdcswitching2> |
| {{ :en:iot-open:hardware2:powering:20231025_130353.jpg?200 | }} | {{ :en:iot-open:hardware2:powering:20231025_130353.jpg?200 | Variable voltage step-down converter module}} |
| <caption>Variable voltage step-down converter module</caption> | <caption>Variable voltage step-down converter module</caption> |
| </figure> | </figure> |
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| <figure dcdcswitching3> | <figure dcdcswitching3> |
| {{ :en:iot-open:hardware2:powering:20231017_172244.jpg?200 |}} | {{ :en:iot-open:hardware2:powering:20231017_172244.jpg?200 | Variable voltage step-down converter module with additional 5V utility power source}} |
| <caption>Variable voltage step-down converter module with additional 5V utility power source</caption> | <caption>Variable voltage step-down converter module with additional 5V utility power source</caption> |
| </figure> | </figure> |
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