MPF32010 Totem Pole Reference Design
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The EVF32010-18831 evaluation board is an AC/DC power factor corrector based on totem-pole topology.
The totem-pole converter has been known for many years, but has not gained popularity until recently. Its main drawback was that very fast transistors were required to block its high voltages. Nowadays, thanks to wide bandgap transistors with fast reverse recovery, this problem has been overcome.
The use of this topology is spreading thanks to its simplicity and efficiency. The ad hoc development of a specific totem-pole power factor correction (PFC) controller and the proper sizing and selection of components enables improved robustness.
Furthermore, time-to-market can be significantly reduced thanks to its integrated GUI.
- 98.5% or Greater Efficiency under Nominal Conditions
- Power Factor above 99% under Nominal Conditions
- 3kW Rated Power
- GUI Interface
- Harmonic Current: IEC 61000-3-2
- Conducted EMC: CISPR 32
- Voltage Sags: IEC 61000-4-11
- Uninterruptible Power Supplies
- Energy Storage
- Server SMPS
Figure 1: EVF32010-18831
1.4. System Description
This converter is composed of one main PCB and four daughter boards:
Figure 2: Hardware Diagram
Figure 3: TP Simplified Circuit
The main components of the power stage are an inductor, a capacitor, and a controlled full bridge. The branch of the full bridge connected to the coil is populated with silicon carbide (SiC) devices, which switch at a high frequency (65kHz). The switches on the lower frequency branch, which commutates at grid frequency, can be implemented with diodes; however, Si transistors are preferred due to their lower conduction losses.
The totem-pole PFC behaves like a boost converter in which the SiC devices are activated complementarily and the Si devices are used as a return path for the current. For a more detailed explanation of the converter’s operation, refer to its datasheet.
Compared to an interleaved boost PFC, a totem-pole PFC has four semiconductor devices instead of eight. Of these four devices, current only flows through two of them at any given moment. In contrast, an interleaved boost PFC has three elements conducting simultaneously, which is why totem-pole topology has better overall efficiency.
Cascodes from UnitedSiC were selected for the fast-switching leg. They have a very good performance including losses and reverse recovery, and in addition they do not require a negative voltage to switch off. Therefore, only a 12V auxiliary voltage is needed to drive all transistors (the high-side supply voltage is obtained with bootstrap operation of the drivers). This simplicity improves the system’s robustness and takes up significantly less board space. The input voltage (VIN) is sensed with voltage dividers, so there is no need to add comparator circuity in order to detect polarity as this is done by the controller’s PLL.
1.5. Related Solutions
This reference design is based on the following MPS solutions:
Table 1: MPS ICs
|MPS Integrated Circuit||Description|
|MCS1802GS-10||DC current sensor|
2.1. Electrical Specifications
Table 2: Electrical Specifications
|VIN||80 VAC to 250VAC|
|Frequency||45Hz to 66Hz|
|Max input current||19.6A|
Figure 25: Standalone Efficiency
Figure 28: Power Factor
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