# Half Bridge Capacitor Voltage-Clamped Series Resonant Converter

Chapter
Part of the Power Systems book series (POWSYS)

## Abstract

In this chapter, a topological variation of the series resonant converter, the half bridge capacitor voltage clamped series resonant converter, is studied. After the presentation of the power converter topology, the qualitative analysis is presented, which includes the description of operation, topological states for each time interval and relevant waveforms. Closed-form solutions for the static gain output characteristics are derived, using the state-plane trajectory analysis technique. In subsequent sections of the chapter, numerical example and numerical simulation are provided to illustrate the theoretical analysis. At the end of the chapter, proposed exercises with answers are included.

## Nomenclature

Vi

Input DC voltage

Vo

Output DC voltage

V1

Half of the DC input voltage

Po

Output power

Po min

Minimum output power

Po max

Maximum output power

Co

Output filter capacitor

Ro

µo

Normalized switching frequency

q

Static gain

D

Duty cycle

fs

Switching frequency

fs max

Maximum switching frequency

fs min

Minimum switching frequency

Ts

Switching period

td

T

Transformer

n

Transformer turns ratio

N1 and N2

Transformer primary and secondary winding turns

$$\text{V}_{\text{o}}^{{\prime }}$$

Output DC voltage referred to the transformer primary side

$$\text{i}_{\text{o}}$$

Output current

$$\text{i}_{\text{o}}^{{\prime }}$$

Output current referred to the transformer primary side

$$\text{I}_{\text{o}}^{{\prime }} \left( {\overline{{{\text{I}}_{\text{o}}^{{\prime }} }} } \right)$$

Average output current referred to the transformer primary side and its normalized value

S1 and S2

Switches

vg1 and vg2

Switches gate signals

DC1 and DC2

Clamping diodes

Cr

Resonant capacitor

Lr

Resonant inductor (may include the transformer leakage inductance)

iLr

Resonant inductor current

ILr$$\left( {\overline{{{\text{I}}_{\text{Lr}} }} } \right)$$

Resonant inductor peak current and its normalized value, commutation current for S1 and S3

ωo

Resonant frequency

z

Characteristic impedance

z1 and z2

State plane impedance

I1$$\left( {\overline{{{\text{I}}_{1} }} } \right)$$

Inductor current at the end of the first and fourth step of operation and its normalized value

vab

Full bridge ac voltage, between points “a” and “b”

vS1 and vS2

Voltage across switch S1 and S2

iS1 and iS2

Current in the switch S1 and S2

∆t1

Time interval of the first step of operation in (t1−t0)

∆t2

Time interval of the second step of operation (t2−t1)

∆t3

Time interval of the third step of operation in (t3−t2)

∆t4

Time interval of the fourth step of operation (t4−t3)

∆t5

Time interval of the fifth step of operation in (t5−t4)

∆t6

Time interval of the sixth step of operation (t6−t5)

IS RMS$$\left( {\overline{{{\text{I}}_{{{\text{S}}\,{\text{RMS}}}} }} } \right)$$

Switches S1 and S2 RMS currents and its normalized value

IDC$$\left( {\overline{{{\text{I}}_{\text{DC}} }} } \right)$$

Diodes DC1 and DC2 average currents and its normalized value

## Reference

1. 1.
Agrawal, J.P., Lee, C.Q.: Capacitor voltage clamped series resonant power supply with improved cross regulation. In: IEEE IAS Annual Meeting, pp. 1141–1146 (1989)Google Scholar 