Description: "Package with models for DC/DC conversion"

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## Buildings.Electrical.DC.Conversion

Package with models for DC/DC conversion

### Information

This package contains models for DC/DC conversion. AC/DC converters can be found in the respective AC package.

Extends from Modelica.Icons.Package (Icon for standard packages).

### Package Content

Name | Description
--- | ---
DCDCConverter | DC DC converter
Examples | Package with example models

## Buildings.Electrical.DC.Conversion.DCDCConverter

DC DC converter

### Information

This is a DC/DC converter, based on a power balance between the two DC sides. The paramater conversionFactor defines the ratio between the two averaged DC voltages. The loss of the converter is proportional to the power transmitted at the second DC side. The parameter `eta` is the efficiency of the transfer. The loss is computed as

Ploss = (1-η) PDC,

where PDC is the power transmitted. This model is symmetric and the power can be transmitted in both directions. The loss is computed depending on the direction of the power flow.

Extends from Buildings.Electrical.Interfaces.PartialConversion (Model representing a generic two port system for conversion).

### Parameters

Type | Name | Default | Description
--- | --- | --- | ---
replaceable package PhaseSystem_p | PartialPhaseSystem | Phase system of terminal p
replaceable package PhaseSystem_n | PartialPhaseSystem | Phase system of terminal n
Voltage | VHigh |  | DC voltage on side 1 of the transformer (primary side) [V]
Voltage | VLow |  | DC voltage on side 2 of the transformer (secondary side) [V]
Real | eta |  | Converter efficiency
Ground
side 1
Boolean | ground_1 | true | Connect side 1 of converter to ground
side 2
Boolean | ground_2 | true | Connect side 2 of converter to ground

### Connectors

Type | Name | Description
--- | --- | ---
replaceable package PhaseSystem_p | Phase system of terminal p
replaceable package PhaseSystem_n | Phase system of terminal n

### Modelica definition

model DCDCConverter "DC DC converter" extends Buildings.Electrical.Interfaces.PartialConversion( redeclare package PhaseSystem_p = PhaseSystems.TwoConductor, redeclare package PhaseSystem_n = PhaseSystems.TwoConductor, redeclare Interfaces.Terminal_n terminal_n, redeclare Interfaces.Terminal_p terminal_p); parameter Modelica.SIunits.Voltage VHigh "DC voltage on side 1 of the transformer (primary side)"; parameter Modelica.SIunits.Voltage VLow "DC voltage on side 2 of the transformer (secondary side)"; parameter Real eta(min=0, max=1) "Converter efficiency"; parameter Boolean ground_1 = true "Connect side 1 of converter to ground"; parameter Boolean ground_2 = true "Connect side 2 of converter to ground"; Modelica.SIunits.Power LossPower "Loss power"; protected parameter Real conversionFactor = VLow/VHigh "Ratio of high versus low voltage"; Modelica.SIunits.Current i1,i2; Modelica.SIunits.Voltage v1,v2; Modelica.SIunits.Power P_p "Power at terminal p"; Modelica.SIunits.Power P_n "Power at terminal n"; equation Connections.potentialRoot(terminal_n.theta); Connections.potentialRoot(terminal_p.theta); if not ground_1 then i1 = 0; else v1 = 0; end if; if not ground_2 then i2 = 0; else v2 = 0; end if; P_p = PhaseSystem_p.activePower(terminal_p.v, terminal_p.i); P_n = PhaseSystem_n.activePower(terminal_n.v, terminal_n.i); v1 = terminal_n.v[2]; v2 = terminal_p.v[2]; sum(terminal_n.i) + i1 = 0; sum(terminal_p.i) + i2 = 0; // Voltage relation v_p = v_n*conversionFactor; // OLD equations that take into account the power at the secondary // power balance // LossPower = (1-eta) * abs(P_p); // P_n + P_p - LossPower = 0; // Symmetric and linear version LossPower = P_p + P_n; if i_n >=0 then i_p = i_n/conversionFactor/(eta - 2); else i_n = conversionFactor*i_p/(eta - 2); end if; end DCDCConverter;