plasma for environment protection
Zachodniopomorski
Uniwersytet
Technologiczny w Szczecinie

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plasma for environment protection
Water cleaning vessel visualisation
Technical parameters of chosen Li-Ion
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Zachodniopomorski
Uniwersytet
Technologiczny w Szczecinie

plasma for environment protection
The West Pomeranian University of Technology contributes to the PlasTEP project i.a. in work package six (Plas ma technologies for water cleaning). According to the project flow and planned milestones the project team was responsible to design and construct a mobile power supply system topology which is suitable for mobile water cleaning vessel application. Initially, vessel visualisation was prepared by giving an overview of possible vessel constructions. One visualisation is depicted in Fig. 1:
Fig. 1: Water cleaning vessel visualisation
Initially, rough estimation provided basic construction data:
• vessel area: approx. 1,5 – 2 m2
• vessel type: free floating
•
•
Also a preliminary agreement was found on the following basic electric parameters:
• average power demand: Pav = 100W
• maximum power demand: uptime: stored energy:
Pmax = 1000W
Ton = 10h
Es = 1kWh
Based on that data a preliminary set of calculations was established. Its results were four possible system confi gurations: stand alone, small photovoltaic panel use, large photovoltaic panel use, fuel cell implementation. All four principles are presented in Fig. 2 – 5 together with basic technical data and a set of most important advan tages/ disadvantages.
3
Zachodniopomorski
Uniwersytet
Technologiczny w Szczecinie

plasma for environment protection
Battery DC/ DC Loads
Fig. 2: Stand alone system principle
Battery:
Lead-acid: 1 kWh = 12 V * 83 Ah
Energy: 30 Wh/kg - 35 kg
Max. power: 150 W/kg - 5,2 kW
Costs = 80 €
+ high power
+ low costs
+ availablity
- unfavorable environment
- high weight
- need for frequent charging
Li-Ion:
Energy: 150 Wh/kg - 7 kg
Max. power: 300 W/kg - 2,1 kW
Costs = 700 €
+ high energy - high costs
+ low weight - difficult handling
- need for frequent charging
DC/ DC Loads
Battery
Solar Cells
Fig. 3: Small photovoltaic panel system principle
Example for solar cell:
Power: 100 W +Reduces battery size and costs
Dimension: 1000 * 800 * 35 mm (0,8 m²) - Additional costs
Voltage: 17 V
Current: 6 A
Energy production estimation: 0,025 kWh/day (winter) up to 0,27 kWh/day (summer)
Costs = 400 €
4
Zachodniopomorski
Uniwersytet
Technologiczny w Szczecinie

plasma for environment protection
Battery DC/ DC Loads
Solar Cells
Super
Capacitors
Fig. 4: Large photovoltaic panel system principle
Example: 5 solar cells
Power max: 100 W * 5 = 500 W +Independence from grid charging
Dimension: 1000 * 800 * 35 mm (0,8 m²) + Small battery
Energy: 0,125 kWh/day (winter) up to - Requires additional components (supercapacitors)
1,35 kWh/day (summer)
Costs = 2000 €
- Higher additional costs
Fuel cell DC/ DC Loads
Li-Jon
Super
Capacitors
Fig. 5: Fuel cell system principle
Example for solar cell:
Power: 100 W +Reduces battery size and costs
Dimension: 1000 * 800 * 35 mm (0,8 m²) - Additional costs
Voltage: 17 V
Current: 6 A
Energy production estimation: 0,025 kWh/day (winter) up to 0,27 kWh/day (summer)
Costs = 400 €
5
Zachodniopomorski
Uniwersytet
Technologiczny w Szczecinie

plasma for environment protection
Due to the additional costs and system maintenance the principle as it is depicted in Fig. 3 was chosen in limited size, weight and with acceptable additional costs. According to this preliminary agreements all system com ponents were ordered, tested and a power supply converter with a switched mode was constructed.
Due to the results of preliminary chemical tests (conducted by IMP PAN, Gdańsk) an additional module had to be considered. This module was based on high power (1000 W) microwave plasma source due to the necessity of water contamination evaporation. Due to that fact a new system principle was proposed as described in follo wing paragraphs.
An additional module was intruduced because of the change in system design. It resulted in a dual-mode supply with a dedicated microwave (MW) plasma storage and converter. An overview of the proposed soultion is given in Fig. 6:
Fig. 6: Supply system (design principle)
The preliminary assumption of 100W of average power was considered as System 1. This system is supplying the water contamination mover motor, a fan, the dielectric barrier discharger (DBD) reactor and small scale seconda ry loads. System 2 is designed in parallel and will be responsible for large loads of the magnetron gun. If it should be necessary the two systems can be operated independently or with a common ground (dotted line). A detailed system description will be given in the following subsections.
6
Zachodniopomorski
Uniwersytet
Technologiczny w Szczecinie

plasma for environment protection
The medium size Li-ion batteries were chosen due to their limited weight, size and excellent performance. In order to limit the excessive costs the overall storage consists of eight modules which are connected in series/ pa rallel as it was desired by the constructor. The most important technical parameters of the chosen Li-Ion energy storage solution are:
1. Type
2. Nominal voltage
3. Minimal voltage
4R(2S∙CGR18650CG/4S4P)
28,8 V
24 V
4. Maximal voltage 33,6 V
5. Stored energy 35,2 Ah (1,18 kWh)
6. Maximal discharge current 32 A
Table 1: Technical parameters of chosen Li-Ion
Fig. 7: System 1 main Li-Ion battery pack
7
Zachodniopomorski
Uniwersytet
Technologiczny w Szczecinie

plasma for environment protection
In accordance to preliminary assumptions and due to the planned operating environment and conditions an auxiliary power source was planned. According to vessel’s size a single module was chosen with an active area of approximately 1 m2. Due to costs a standard solution was chosen. Finally, an RS-M155 panel by RICOH SOLAR was planned. All basic parameters of the chosen panel are given in Table 2:
1. Model
2. Maxiamal power
3. Size
4. Voltage in MPP
RS-M155
155 W
1580 x 808 x 45 mm
34,3 V
5. Output current in MPP 4,52 A
6. Short circuit current
7. Efficiency
4,90 A
12,4 %
Table 2: Main technical properties of the RS-M155 panel
Fig. 8: RICOH SOLAR RS-M155 photovoltaic panel
8
Zachodniopomorski
Uniwersytet
Technologiczny w Szczecinie

plasma for environment protection
Based on these technical parameters the main characteristics for different irradiations and panel temperatures were calculated. The results are given in Fig. 9:
Fig. 9: RS-M155 panel characteristics; left: variable irradiance, right: variable panel temperature
The maximum power point varies as a function of both parameters. In order to estimate an available solar power and, therefore, calculate the estimated state of charge of the main energy storage, a Homer Energy software was used for the estimated north Poland conditions (53º26’N 14º32’E). Assuming a maximal panel output power and the estimated converter efficiency, a set of calculations was led for statistical weather data. The estimated output power of the panel as a function of the time of day and year is shown in Fig. 10:
Fig. 10: Calculation results of the photovoltaic panel output power as a function between time of day and year
Assuming the average power consumption of 70W and a 7h system continuous operation, a state of charge of
Li-ion batteries can be established. Results are given in Fig. 11.
9
Zachodniopomorski
Uniwersytet
Technologiczny w Szczecinie

plasma for environment protection
Fig. 11: Calculation results of the Li-ion batteries state of charge
In most parts of the year the state of charge of the batteries exceeds 30% which is crucial for their proper operation and lifetime. In summer it is assumed that the panel will be able to cover the average power demand of the supply System 1.
Because of specifics of a Li-ion battery charging process and the necessity to track the maximum power point of the panel, a dedicated power electronic switched mode power supply (SMPS) was developed. A typical charging process of a Li-ion battery is depicted in Fig. 12:
Fig. 12: Typical charging process of a Li-ion battery
Therefore, the main functionality of such a module is:
• Monitoring of the battery‘s state of charge and charging process,
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Maximum power point tracking of the panel (when applicable),
Power flow control,
Parameter monitoring and storage,
10
Zachodniopomorski
Uniwersytet
Technologiczny w Szczecinie

plasma for environment protection
•
•
Communication and
Safety routines.
A simplified construction of the final topology is depicted in Fig. 13:
Fig. 13: Principal design of the SMPS converter
The components C1, C2, T1, L1 and D1 represent a classical buck converter topology. The switch T2 enables an auxiliary load disconnection. In order to control the state of that switch a small-scale photovoltaic contactor
PVI5080N was implemented. The converter currents are measured using precise 10mΩ and 5mΩ shunts and
INA169 sensors. The main controller includes an eight bit fast microcontroller AT90PWM3B by Atmel.
Fig. 14: Constructed SMPS converter; left: microcontroller board, right: SMPS
In case of larger computational power an adapter board was prepared. It allows a fast controller exchange with the DSP processors eZdsp TMS320F2812 by Texas Instruments. The constructed prototype is depicted in Fig. 14.
Fig. 15, 16 and 17 give an overview of the system’s schematics and the resulting layout. Its design was prepared by using the Eagle environment.
11
Zachodniopomorski
Uniwersytet
Technologiczny w Szczecinie

plasma for environment protection
Fig. 11: Calculation results of the Li-ion batteries state of charge
Fig. 15: CAD design of the controller board; schematics
Fig. 16: Converter board layout top layer
12
Zachodniopomorski
Uniwersytet
Technologiczny w Szczecinie

plasma for environment protection
Fig. 17: Converter board layout bottom layer
In order to verify the system operation, an exhaustive test programme followed. Fig. 18 presents the measurement results of the battery charging mode, Fig. 19 gives an overview of the overall system operation during variable load.
Fig. 18: System operation in battery charging mode
13
Zachodniopomorski
Uniwersytet
Technologiczny w Szczecinie

plasma for environment protection
Fig. 19: System operation under different loads
The power direction changes under variable loads. In the first region (approx. 320 seconds), due to the low load, the excessive power of the photovoltaic panel is used to charge the battery pack. In the second region (320 – 500 seconds), due to the increase of the load power, only about 50W are used for battery charging, the rest is used for load supply. In the high load region (700 – 850s) all power of the panel is used together with the full battery current to supply the load. System behavior is stable and as assumed.
Another functionality is the maximum power point tracking (MPPT) operation in a constant current mode. The system performance is shown in Fig. 20. The system maintains the maximum power (MPP was 82 W) indepen dent of the change of the load. In all cases the converter efficiency was in the range 95 – 96,5%.
Fig. 20: System operation in MPPT mode
14
Zachodniopomorski
Uniwersytet
Technologiczny w Szczecinie

plasma for environment protection
Because of the large amount of the power which required for a constant MW plasma reactor operation, an addi tional storage was necessary. Different storage systems were analysed and the possibilities are given in Table 3.
Type
Producer
Nominal voltage [V]
Nominal capacity
[Ah] (C20)
Nominal capacity
[Ah] (C6)
Self discharge
[%/ month] 20ºC
Maximal discharge current
Weight [kg]
Dimensions [mm]
DxWxS
Mounting
Price netto
AGM-130Ah
Mastervolt http://www.
mastervolt.
com/
12
130
108
3
0,3 C
37,6 36 36
408x227x176 330x241x171 409x225x173
M 8
248 €
DP31DT
Marine Master
Deka http://www.
dekabatteries.
com/
12
115
100
2
0,3 C different
HZY-MR12-120
Haze http://www.
hazebatteryu sa.com
12
120
100
3
0,2 C
M 8
LUCAS http://www.
lucas-batteriesonline.co.uk/
12
110
ODYSSEY http://www.
odysseybattery.
com
12
126
855 zł (~ 217 €) 840 zł (~ 214 €) 560 zł (~ 142 €)
Table 3: Possible „Marine“ type energy storages
LXV31MF
90 n.d.
0,1 C
23 (?) n.d.
n.d.
PC2250
104 n.d.
3 C
39
286x269x233 n.d
475 € 1 n.d. = no data
1 = transport costs included, possible discount
Due to excellent performance and proven quality Oddysey batteries were proposed, for possible 1 hour opera tion 2 x PC2250 type. Main properties of the solution include:
• 2, 3 or 4 year full warranty
• 12 year military design
• Drycell sealed technology
• 60% more cranking power
• Deep cycle design
15
Zachodniopomorski
Uniwersytet
Technologiczny w Szczecinie

plasma for environment protection
•
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Deep cycle design
Mount in any position and at any place
Brass terminals, non-corrosive
Steel jacket for severe use
2 x PC2250 – 2 x 475 Eur
About an hour of operation
2 x 39 kg
An exemplary design of such battery is depicted in Fig. 21:
Fig. 21: System operation under different loads
Fig. 22: O verview of the full supply system design proposal
16
Zachodniopomorski
Uniwersytet
Technologiczny w Szczecinie

plasma for environment protection
The power supply system design proposal was described including a low power li-ion based System 1 with pho tovoltaic panel source and basics of high-power System 2 storage. A dedicated microcontroller-based converter was designed allowing for power flow control, MPP tracking and battery charging. A high efficiency of 95% was reached.
In case of MW plasma different storage technologies were compared and resulted in classic lead-acid marine technology. Magnetron supply is still under investigation. However, an inverter-based solution is planned with intermediate DC/DC SMPS control.
17
Zachodniopomorski
Uniwersytet
Technologiczny w Szczecinie