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1. ANALYSIS AND DESIGN OF HIGH GAIN SOFT-
SWITCHING BIDIRECTIONAL DC-DC
CONVERTER WITH PPS CONTROL
Presented by:
Neha
13EE27

2. Contents
• Introduction
• Why PPS control?
• Circuits used in HSBDC
• Operating Principle
• Analysis and Design
• Design Comparison
• Conclusion
• References

3. Introduction
• It is a bidirectional DC-DC converter which uses
phase shift angle to control the direction of
amount of power flow while the duty cycle is
used to balance the voltage between two high
voltage side(HVS) capacitors.
• It uses soft switching in both forward and
backward modes at all load under wide voltage
range .
• It uses PWM plus phase shift(PPS) control for non
isolated high gain soft-switching bidirectional DC-
DC converter (HSBDC).

4. Why PPS control ?
• The PWM control method aims at optimizing switching
characteristics by controlling delay times for switches , but
it gives rise to asymmetrical operation in the forward and
backward modes.
• In that control method to achieve soft switching the delay
time must vary continuously according to load and voltage
variation . So required delay times increased as load
power or voltage gain increase , which results in increased
voltage unbalance between capacitors on the HVS.
• Due to this unbalance voltage , increases voltage stress of
the high voltage side (HVS) capacitors and switches.

5. • To overcome the problems occurring due to PWM , PPS
control is used.
• The PPS control method uses two control variables,
phase sift angle ϕ and duty cycle D.
• The phase sift angle is used to control the direction and
amount of power flow while the duty cycle is used to
balance the voltage between two capacitors on the
HVS .
• Delay time is not required for the proposed PPS
method . Therefore, the effective step-up/down gain
are not affected by load and voltage variation , thereby
ensuring soft-switching at all load and voltage
conditions.

6. Circuits used in HSBDC
• Above two half bridge cells are connected via auxiliary
capacitor Ca to in such a way that two output
capacitors C1 and C2 are connected in series to obtain
high step-up gain , resulting in the HSBDC.

7. HSBDC Circuit

8. Operating Principal
• The LVS switches S1 and S2 are operated
complementary switching with duty cycle D
and 1-D , respectively .similarly , the HVS
switches S3 and S4 are operated
complementary switching with duty cycle D
and 1-D , respectively .
• The phase sift angle ϕ is defined as the angle
between the gate drive signals of S1 and S3.

9. • In forward mode ,gate drive signals of S1 leads that for S3 (ϕ >
0), so the power is delivered from LVS to HVS.
• In backward mode, gate drive signals of S1 lags that for S3(ϕ <
0), so that power is delivered from HVS to LVS .

10. • The operation modes and key waveforms of
the HSBDC with PPS control for forward
operation are describe below:-
• the switching cycle can be divided into eight
stages which are explained as follows.
• Mode 1 [t0–t1]:-

11. • This mode begins when S2, which was
carrying the difference in current between iLa
and iLf is turned OFF. The gating signal for S1
is applied during this mode, and S1 is turned
on under the ZVS condition. Inductor
currents iLa and iLf start to decrease and
increase, respectively, with the slopes
determined by the following equations:

13. • Mode 2 [t1–t2]:
When the increasing current iLf become greater
than the decreasing current iLa, the current
flowing through S1 is reversed. During this
mode, iLa and iLf keep flowing with the same
slope determined in Mode 1

14. • Mode 3 [t2–t3]:
• This mode begins when iLa is reversed. Both
the inductor currents iLf and iLa flows through
S1. During thismode, iLa and iLf keep flowing
with the same slope determined in Mode 1.

15. Mode 4 [t3–t4]:
• This mode begins when S4, which was carrying iLa is
turned OFF. The gating signal for S3 is applied during
this mode, and S3 is turned on under ZVS condition.Vca
is equal to VC1, therefore, the slope of the current
flowing through La is zero, which means that iLa is
constant in this mode.

16. • Mode 5 [t4–t5]:
• This mode begins when S1, which was carrying
both iLa and iLf is turned OFF. The gating signal
for S2 is applied during this mode, and S2 is
turned on under ZVS condition. Both iLa and iLf
start to decrease, with the slopes determined by
the equations given in next slide:

17. • Mode 6 [t5–t6]:

18. • This mode begins when iLa is reversed. The
difference in current between iLf and iLa flows
through S2.During this mode, iLa and iLf keep
flowing with the same slope determined in
Mode 5.
• Mode 7 [t6–t7]:

19. • This mode begins when S3, which was carrying iLa is
turned OFF. The gating signal for S4 is applied during
this mode, and S4 is turned on under ZVS condition.
Vca is equal to VC2, therefore, the slope of the
current flowing through La is zero, which means that
iLa is constant in this mode.
• Mode 8 [t7–t8]:

20. • When the decreasing current iLf becomes than
constant current iLa, the current flowing through
S2 is reversed. During this mode, iLf keeps
flowing with the same slope determined in Mode
5, while iLa remains constant. This is the end of
the switching cycle. At t0, S2 is turned off, and
this switching cycle is repeated.
• Detailed explanation of operation modes and key
waveforms of the HSBDC with PPS control for
backward operation is omitted here, since the
operating principle of the backward operation is
symmetrical to the forward operation.

21. Analysis and Design
• To obtain both the optimal duty and step-
up/down gain of the HSBDC with PPS control,
it is assumed that voltages across C1, C2, and
Ca are constant during the switching period
Ts. The output voltage is given by:

22. • VC1 and VC2 are the output voltages of HB cell
1 and HB cell 2, respectively. Therefore, they
can be expressed as follows:
The average value of the voltage across the
inductor is zero, therefore:
• Since PPS control makes voltage balance
between capacitor at load side , so

23. • After combining all equations, the step-
up/down gain of the converter becomes:
Finally, the desired duty cycle of switches S1 and
S2 can be obtained as:
The power equation can be expressed as
follows:

24. • From the waveform of forward mode, the
average value of is4 can be calculated as
follows:
• Since is4 and ihr are same in magnitude so
power equation for forward mode can be
obtained as follows:

25. • Power equation of the backward mode can be
calculated in the same way and expressed as
follows:
• In the forward (backward) mode, the
maximum transferred power Pmax (−Pmax)
occurs at the maximum available phaseshift
angle ϕmax (−ϕmax). Therefore, the
regulating range of the phase-shift angle ϕ of
the converter is from −ϕmax to ϕmax. From
ϕmax and Pmax can be obtained as follows:

26. • Power curves versus phase shift angle :

27. Design Comparison
• In this section, the HSBDC with PPS control and
conventional half-bridge converter are designed
under a specification and design results are
compared.
• Although numbers of switches and capacitors of
the HSBDC with PPS control are higher than those
of the conventional half-bridge converter, voltage
ratings of the components are half compared to
the conventional half-bridge converter, thereby
making selection of the components more
flexible.

29. Conclusion
• By utilizing two control parameters, the
switching patterns for bidirectional operation
of the HSBDC with PPS control become
symmetrical, which results in increased design
flexibility, seamless power flow change
without using complicated control method,
increased soft-switching range under wide
voltage range, and identical voltage ratings of
components.

30. References
• M. Aamir, S. Mekhilef and H. J. Kim, “High-Gain Zero-Voltage Switching
Bidirectional Converter With a Reduced Number of Switches,” IEEE Trans.
Circuits Syst. II, Express Briefs, vol. 62, no. 8, pp. 816–820, Aug. 2015.
• M. Uno and K. Tanaka, “Single switch cell voltage equalizer using
multistacked buck boost converters operating in discontinuous conduction
mode for series connected energy storage cells,” IEEE Trans. Veh. Technol.,
vol. 60, no. 8, pp. 3635–3645, Oct. 2011.
• M. Uno and A.Kukita, “Bidirectional PWM converter integrating cell
voltage equalizer using series-resonant voltage multiplier for
seriesconnected energy storage cells,” IEEE Trans. Power Electron., vol. 30,
no. 6, pp. 3077–3090, Jun. 2015.
• Y. Hsieh, J. Chen, L. Yang, C. Wu, and W. Liu, “High-conversion-ratio
bidirectional DC–DC converter with coupled inductor,” IEEE Trans. Ind.
Electron., vol. 61, no. 1, pp. 210–222, Jan. 2014.
• H. Wu, Y. Xing, Y. Xia, and X. Ma, “A family of non-isolated three-port
converters for stand-alone renewable power system,” in Proc. IEEE IECON,
2011, pp. 1030–1035.