High gain DC-DC converter based on charge pump circuit … · (Simulation Program with Integrated Circuit Emphasis). SPICE is an industry standard software generally used to simulate

High Voltage Gain DC-DC Converter based on Charge Pump Circuit Configuration with Voltage

Controller

Channareth Srun Electrical Engineering Department University of Hasanuddin, UNHAS

Makassar, Indonesia [email protected]

Faizal Arya Samman Electrical Engineering Department University of Hasanuddin, UNHAS

Makassar, Indonesia [email protected]

Rhiza S. Sadjad Electrical Engineering Department University of Hasanuddin, UNHAS

Makassar, Indonesia [email protected]

Abstract—This paper presents the high output voltage DC-DC converter that combines two circuit configurations, i.e. a two-phases interleaved boost on the input side and a charge pump circuit configuration based on voltage multipliers on the output side. When loads change, the converter output voltage also changes. Therefore the converter output voltage is needed to control. The input voltage range of the proposed converter is between DC 12V-24V, which is fed from batteries. Before designing the circuit, the converter system is firstly modeled and simulated using SPICE. The control unit, which is implemented by a control software and embedded into a microcontroller, generates two PWM signals to drive the converter output voltage constant at the 220V setpoint. The performance of the controller is tested with the changes of load conditions at the output terminal and the change of DC voltage at the input terminal. The simulation results shows that the control unit can maintain the output voltage at the expected value. This performance result will be useful to develop a home scale photovoltaic system in the future. (Abstract)

Keyword : High voltage gain DC-DC, Charge Pump, PWM, Voltage Controller (keywords)

I. INTRODUCTION

High voltage gain dc-dc converter operating at high voltage regulation has been widely used in industrial application or for electronic equipment such as high-intensity-discharge lamps for automobile headlamps, X-ray power generator, servo-motor drives, computer periphery power supply and UPS (uninterruptible power supplies) [1]. They also can used to interface with low voltage sources such as photovoltaic (PV) panels, fuel cells, batteries, etc., to the 220-V dc for coupling the rectified voltage from the grid with dc batteries as shown in Fig. 1.

Currently, there are many researches have been achieved high voltage conversion ratio, a high voltage gain dc-dc converter using a boost stage followed by voltage multiplier (VM) cells have been proposed in [2-4]. A hybrid boosting converter (HBC) with collective advantages of regulation capability from its boost structure and gain enhancement from its voltage multipolar structure is proposed in [2]. The Switched-Capacitor (SC) structure sharing with an inductor energy storage cell boost and buck-boost is proposed in [3]

and the SC based active network converter has a discontinuous input current ripple due to the series and parallel connection of the inductors in its two mode operation is proposed in [4]. The high-frequency transformer and high voltage gain using winding-cross-coupled inductors or integrating coupled-inductor have been proposed in [5, 6].

Similar high voltage gain dc-dc converter used of voltage multiplier (VM) cells derived from the Dickson charge pump with resembles a two-phase interleaved boost converter on the input side that can draw power from a single source or two independent sources has been proposed in [7]. A high-voltage gain dc-dc converter based on modified Dickson charge pump voltage multiplier circuit configuration has been proposed [8], it requires less diode and also lower voltage rating capacitor for its VM circuit compared with [7].

Our paper presents the development of a high voltage gain dc-dc converter based on modified Dickson charge pump circuit configuration proposed in [8] with voltage controller by using interpolated adaptive PI control to maintain the output voltage constant at 220V set point due to batteries input voltage from 12V or 24V with the changes of load conditions. Furthermore, this converter is used in order to avoid the damaged of the diode due to reverse breakdown over-voltage when during coupling the rectified voltage from the grid with voltage dc from batteries.

Fig. 1. Photovoltaic system powered by renewable energy.

The rest of the paper structure is organized as follows. Section II presents the converter circuit modeling using SPICE

(Simulation Program with Integrated Circuit Emphasis). SPICE is an industry standard software generally used to simulate analog and digital circuits. The simulation result is presented in Section III. Section IV presents the testing the result of converter circuit with adaptive PI control. This section shows us the output voltage analysis of the circuit tested with the changes of input and load conditions. And, then the conclusion and outlooks are presented in Section V.

II. SYSTEM MODELING

The high gain dc-dc converter circuit is modeled using SPICE program. The signal generator is also modeled in the SPICE. The schematic of the circuit is illustrated in Fig.2. The circuit is designed with two-phase interleaved boost converter on the input side and modified Dickson charge pump circuit configuration on the output side [8]. We can also design with conventional Dickson charge pump circuit configuration on the output side or with two input sources [7].

Fig. 2. DC/DC Converter Circuit Schematics with PI Controller. The two MOSFETs, used as switching devices, i.e. M1, M2 driven by two gate driver from comparator. In general, insulated-gate bipolar transistor (IGBT) used for replaced of MOSFET as switching devices [9]. MOSFETs technology based on Silicon Carbide (SiC) has been improved power output and its operating-voltage level, while Gallium Nitride (GaN) material has better switching speed are better than conventional MOSFETs [10,11]. Four Diode, D1, D2, D3 and D4 are respectively operate as self-timed switches characterized by a forward bias voltage and the multiplier operates similar to a bucket-brigade delay line, by pumping packets of charge along the diode chain as the coupling capacitors are successively charged and discharged during each half of the clock cycle [12].

As shows in Fig.2, there are five voltage controlled voltage sources used for controlled voltage sensor, voltage error, PI voltage controller and two comparators. That both comparators is used to generate PWM signal, which is then powered-up by M1 and M2. In the circuit we give the circuit node numbers, which are used as the reference number for each waveform in the simulation results.

In this paper is simulated PI analog parameters used SPICE, where PI parameters can be found through exploration techniques parameters simulation. We get the data for some

value of Kp and Ki from input voltage ranges 12-24V and measure load current. The load current can be measured by modeled in SPICE using voltage source Vx =0, while Vy=0 is voltage source for measured the input current as shown in Fig.2. There are two criteria used to find best Kp and Ki such as Average Absolute Value Error (AAVe) and Maximum overshoot (Mp). The best constant values Kp and Ki is the smallest value of AAVe and Mp. Then, the determined the best value of Kp and Ki can obtained from the average value of AAVe and Mp taken by a few input voltage and load resistances changed.

III. SIMULATION RESULT

Fig.3 and Fig.4 shows the simulation result of AAVe with the variation parameters of Kp and Ki for input voltage 12-24V with difference load resistances value between 100Ω to 1kΩ. The graphs shows the best value of Kp(AAVe) and Ki(AAVe) which, is the small values of AVVe. Fig.5 and Fig.6 shows the simulation result of Mp with the variation parameters of Kp and Ki for input voltage 12-24V with difference load resistances value between 100Ω to 1kΩ. The graphs shows the best value of Kp(Mp) and Ki(Mp) which, is the small value of Mp. The value Kp* is a value of Kp from average value while, the Ki* is a value of Ki from average value.

Kp*= (Kp(AAVe)+ Kp(Mp))/2 (1) Ki*= (Ki(AAVe)+ Ki(Mp))/2 (2)

∆V is voltage from the input voltage subtracts with the

voltage reference. ∆V=Vin − Vref (3)

TABLE I. THE BEST VALUE OF KP* AND KI

* FROM AVERAGE VALUE

Vin (V)

Criteria of AAVe and Mp

Measured load

current

Output voltage

Load value

Kp* Ki* ∆V

12V

2.2008A 220.078V 100Ω 20 25

-208V 731.672mA 219.501V 300Ω 15 20

439.950mA 219.977V 500Ω 5 25

220.613mA 220.613V 1kΩ 10 17.5

24V

2.1990A 219.939V 100Ω 10 20

-196V 733.171mA 219.951V 300Ω 10 30

440.682mA 220.341V 500Ω 5 30

220.984mA 220.98V 1kΩ 5 5

The best value of Kp and Ki shown in table I, we created

the trendline models to get the equation in accordance with data of Kp and Ki are also used with any values of input voltages and load resistances conditions. Fig.8 shows the trend line model from the best Kp and Ki, from the model we obtained polynomial equation for the best value of Kp and Ki from the conditions.

(a)

(b)

(c)

(d)

Fig. 3. The simulation result of AAVe with variation parameter Kp and Ki for input voltage 12V connected with load resistance (a) 100Ω, (b) 300Ω, (c) 500Ω, (d) 1kΩ.

(a)

(b)

(c)

(d)

Fig. 4. The simulation result of AAVe with variation parameter Kp and Ki for input voltage 24V connected with load resistance (a) 100Ω, (b) 300Ω, (c) 500Ω, (d) 1kΩ.

(a)

(b)

(c)

(d)

Fig. 5. The simulation result of Mp with variation parameter Kp and Ki for input voltage 12V and load resistance (a) 100Ω, (b) 300Ω, (c) 500Ω, (d) 1kΩ.

(a)

(b)

(c)

(d)

Fig. 6. The simulation result of Mp with variation parameter Kp and Ki for input voltage 24V and load resistance (a) 100Ω, (b) 300Ω, (c) 500Ω, (d) 1kΩ.

Fig. 8. Trendline model for the best Kp and Ki with input voltage 12-24V and load between 100Ω to 1kΩ

• When we connected with load less than 100Ω, the polynomial equations are:

Kp1= -0.8333.∆V − 153.33 (4)

Ki1= −0.4167.∆V − 61.667 (5)

• When we connected with load ranges between 100Ω to 300Ω, the polynomial equations are:

Kp2= −0.4167.∆V − 71.667 (6)

Ki2 = 20 (7)

• When we connected with load ranges between 300Ω to 500Ω, the polynomial equations are:

Kp3 = 5 (8)

Ki3 = 0.4167.∆V+ 111.67 (9)

• When we connected with load ranges bigger than 500Ω, the polynomial equations are:

Kp4= −0.4167.∆V − 76.667 (10)

Ki4 = −1.0417.∆V − 199.17 (11)

IV. TESTING SIMULATION RESULTS

We already modeled of circuit in SPICE program. Fig. 9 presents the three subplot views. The first line is the limit level (straight line) and the two carrier signals in sawtooth wave form. Two signals sawtooth are used to generate PWM control signal for the gate drivers M1 and M2 as presented in second line and third line of Fig.9.

Fig.10 presents the simulation result by using PI adaptive controller with Vin and Rload are changed are views of three subplot diagram. The first line is the input voltage. The second line is PI voltage controller and the third line is the output voltage. In this simulation, there are 12V-DC and 24V-DC input are applied into the input port and there are load 100Ω, 300Ω, 500Ω and 1kΩ are connected to output port of the converter circuit.

Fig. 10(a) shows the simulation when we used input voltage 24V-DC and 12V-DC connected with load 100Ω while, Fig. 10 (b) shows the simulation when we used input

ranges 12V-DC to 24V-DC connected with load changed such as, 100Ω, 300Ω, 500Ω and 1kΩ.

Time

0s 10us 20us 30us 40us 50usV(13)

0V

10V

20VV(11)

0V

10V

20VV(30) V(31) V(28)

0V

2.5V

5.0V

SEL>>

Fig. 9. Limit level, Carrier and the generated PWM signals

Time

0s 10ms 20ms 30msV(8)

0V

200V

400V

SEL>>

V(27)-100V

0V

100VV(1)

0V

20V

40V

(a)

Time

0s 10ms 20ms 30msV(8)

0V

200V

400VV(27)

-100V

0V

100VV(1)

0V

20V

40V

SEL>>

(b)

Fig. 10. Simulation result by using PI adaptive controller with (a) input voltage changed by connected with load 300Ω, (b) input voltage changed by connected with load changed from 100 Ω, 300Ω, 500Ω, and 1kΩ.

Fig. 11 shows the simulation of overshoot voltage when connected with input voltage range 12-24V and difference load. Fig.12 shows the comparison of adaptive PI with static PI control. Table II shows the simulation result about value of Average Absolute Voltage error and Maximum overshoot by using PI adaptive controller.

Fig. 11. The overshoot voltages when connected by difference loads.

Fig. 12. The comparison of adaptive with static PI control.

TABLE II. DATA RESULT OF CONVERTER USING PI ADAPTIVE

Vin (V) ADAPTIVE

Load AAVe Mp

12-24V

100Ω 453.474uV 220.072V

300Ω 2.5999mV 220.597V

500Ω 1.2349mV 220.306V

1kΩ 909.629mV 223.782V

V. CONCLUSIONS

This paper has presented high gain DC-DC converter based on charge pump circuit configuration with voltage controller. The performance of this converter with output voltage maintains at set-point and over the change of the input voltage

and the load values has been evaluated. The converter modeled with PI adaptive using polynomial equation in accordance with value of Kp and Ki are also can used with any value of input voltages ranges and load resistances changed.

The converter output voltage are analyzed, as the input voltage ranges is applied to the converter’s input and the load value ranges is applied to the converter’s output terminal. The current flow through a load measured by SPICE program. Therefore the value of load resistance can be found by using Ohm’s law. The analysis is done with different of input voltage ranges and value of load resistances. The simulation result shows that PI adaptive and PI static are difference slightly. To find the best value of Kp and Ki have to criteria PI static for several time. By using PI static can control the output voltage level of the converter. But PI adaptive is better for small overshoot voltage compared with PI static. This converter performance result will be useful to develop a home scale photovoltaic system in the future.

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