H-bridge

Four-quadrant DC chopper: fire_p switches out+ and fire_n switches out− between the input rails; drive fire_n with the complement of fire_p for bipolar switching.

  • Boolean
  • electrical
  • Modelica Standard Library
  • 6 ports
  • 2 parameters
BlockH-bridgeKindhBridgeLibraryConverters

Description

A four-quadrant DC chopper made of two half-bridge legs across the input. Leg p drives dc_p2 and leg n drives dc_n2; each leg has two transistors with antiparallel diodes.

Each fire input controls one leg: true turns on its upper transistor, false its lower transistor. The complement is generated inside, so a leg cannot short the input.

Example

H-bridge and single-phase inverter An H-bridge driving an RL load with 75 % duty, and an inverter leg making 50 Hz AC from a split supply.

Duty H 0.75PWM 10 kHz24 VGroundH-bridgeR 2 ΩL 10 mHi load12 V upper12 V lowerMidpointDuty 50 HzPWM 50 HzInverter legLoad 10 ΩGround (load)v ACGround (v AC)
In Gradara, select a H-bridge block and press F1, then choose Open example. It opens as a new model in My models, ready to run.

Also in this example:DC voltageVoltage sensorCurrent sensorConstantGroundSine waveResistorInductorPWM generatorInverter (1-phase)

Ports

Inputs 2

  • f+fire_pBoolean

    Leg p command: true connects dc_p2 to dc_p1, false to dc_n1.

  • f−fire_nBoolean

    Leg n command: true connects dc_n2 to dc_p1, false to dc_n1.

Conserving terminals 4

  • in+dc_p1electrical

    DC supply positive terminal.

  • in−dc_n1electrical

    DC supply negative terminal.

  • out+dc_p2electrical

    Output terminal of leg p.

  • out−dc_n2electrical

    Output terminal of leg n. Not connected to dc_n1.

Parameters

  • Transistor on resistanceRonTransistor0.00001 Ω

    ≥ 0

    On resistance of each transistor, in ohms. 0 or more.

  • Diode on resistanceRonDiode0.00001 Ω

    ≥ 0

    On resistance of each freewheeling diode, in ohms. 0 or more.

Equations

Modelica
v2 = dc_p2.v − dc_n2.v, v1 = dc_p1.v − dc_n1.v
fire_p and not fire_n: v2 = +v1; fire_n and not fire_p: v2 = −v1; fire_p = fire_n: v2 = 0
Bipolar PWM (fire_n = not fire_p), duty cycle d: mean(v2) = (2d − 1) · v1

Implementation

Modelica Standard Library 4.1.0Modelica.Electrical.PowerConverters.DCDC.HBridge
MSL documentation

Assumptions and limitations

  • Ideal switches: transistors are GTO-type switches that conduct only forward, and diodes switch at 0 V. Off conductance is fixed at 10 µS and knee voltages at 0 V. No switching times, reverse recovery, or conduction voltage drop beyond the on resistance.
  • No dead time between the upper and lower switch of a leg.

Tips

  • For bipolar PWM, drive fire_p from fire and fire_n from notFire of one PWM generator; a duty cycle of 0.5 gives zero mean output.

See also

Select a block in Gradara and press F1 to open its page offline.