XC-Sjælland

Guide to build your own e-Winch

 

Build your own Hangglider and Paraglider Winch

This is a guide to build an electric winch based on a wide range of easy accessible components.

It will be continuously updated.

System description

The thoughts behind this design, was to make a winch with optimal performance, flexible design, with as less mechanical complexity as possible and build by simple and cheap techniqes that everyone can do with basic tools, and by easy accessible components.

 

The motor is an industrial 230/400VAC induction motor with and is controlled by industrial frequency converter with torque limitation function.

 

A stepmotor is used to wind up the wire in equal layers on the drum. The synchronization of the sled and drum overall control of the winch is done by a industrial PLC.

 

The battery pack is based on lead acid batteries from UPS. Each battery has a voltage of 12V and 50 batteries are put in serial connection to have a total voltage end of charge voltage of 700VDC. A little ventilation channel is made to exhaust the gasses when charging.

 

The winches are put on a closed trailer to protect it from rain and to make it easily portable.

 

The wire cutter is based on a 25mm width hobby knife blade, which is placed in an angle 2 x 45° to the wire.

 

The main dimensions are based on the drum which is Ø129x1200mm. The height of the motor is 132mm from the feed to center of the shaft.

Overall Design Parameters

Equation

The most important questions are:
– How much force do you want?
– How much speed do you requirer?

 

Our expirences are 120kg and 60km/h for both hanggliders

and paragliders.

Design of motor

The graph shows the charateristics of and induction motor at nominal current.

As we want do utilize the motor as much as possible, the motor can be overloaded with up to 180% of the nominal torque.

Paraglider and hangglider winches operates only up to slightly above the base speed, as the peak power is dramatically reduced above the base speed.

Thermal overload is not a problem, as the duty cycle of the motor is low. A tow takes about 3 minutes and before the next pilot is ready 3-10 minutes has typically past.

One more technique to get more power of an industrial motor is to use a motor with a 230/400V winding and use 87Hz-technique. It simply means that you couple the motor in delta-connection and supply it with 400VAC and 87Hz instead of 50Hz.

 

By using this technique the torque at 87Hz is heavily increased without stressing the motor.

 

Read more about this right here:
https://vesselautomation.com/scalar-control-of-vfds-87-hz-characteristic/

 

A standard Siemens 4-pole motor can handle up 4200 rpm, and 5600 rpm with improved bearings, so it is no problem to operate above 50Hz from a mechanical perspective.
A standard 6-pole can handle up to 3600 rpm according to the datasheet.
However, even with 87Hz-technique, is not desirable to operate above 120Hz, as the peak power is reduced.

The table shows some examples of different motor configurations and their performance with a Ø129mm drum.

The “Utility factor” is the product of “overspeed factor” times “overload factor”. This value should not be more than 2-2.5 depending on the overspeed factor, as this is the physical power limit of an induction motor.

Overspeed factor 1.0: Utility factor < 3

Overspeed factor 1.1: Utility factor < 2.8

Overspeed factor 1.2: Utility factor < 2.6

Overspeed factor 1.3: Utility factor < 2.5

Overspeed factor 1.4: Utility factor < 2.3

Overspeed factor 1.5: Utility factor < 2.1

Overspeed factor 1.6: Utility factor < 1.9

Overspeed factor 1.7: Utility factor < 1.7

Overspeed factor 1.8: Utility factor < 1.6

Overspeed factor 1.9: Utility factor < 1.4

Overspeed factor 2.0: Utility factor < 1.2

 

These numbers yields as long the battery voltage at load is above the nominal voltage, which is 570VDC*

Read more about the optimal battery voltage in “design of battery”.


Most optimal choice would probably be the “5,5kW 6-pole motor” connected for 87Hz and 400VAC.


*Reference: Siemens motor catalog (Tb/Trated)

The mechanical dimension are the same for all the motor configurations above, as they are standard norm motors. Only the length differs.

See mechanical drawings here:

5,5kW 6-pole motor
7,5kW 6-pole motor
7,5kW 4-pole motor
11kW 4-pole motor

Choice of wire

The answer is simple… use Liros DC500: 
https://www.liros.com/catalog/en/dc-500-p2047/?variant=171

 

It is a quality wire, which costs around 500-600€ for 1000m.

 

We have tried the even thinner Liros DC Pro that is only Ø1.6mm, and it is still easy to splice it with the right tool.

For this just bend a welding thread, then you have the perfect tool.

 

Cheaper type of wires are more thick and does not last as long as quality wires. A thick wire has more disadvantages:
– More volume of wire on the drum increase the risk of wire mess

– Requires more power from the sled stepper motor

– Generates more drag in the air, which means less altitude

 

Design of drum

The diameter of the drum is based on the perfect speed range of an 4 to 6-pole induction motor in relation to towing hang- and paragliders.

Ø129mm is equal to 5 inches, which is a quite common size for pipes and are easy accessible.

 

To minimize workload, sprocket carriers from a gocart can be used together with a pipe to form the drum.

Depending on the thinkness of the drum, an aluminium adaptor may be needed.
6 holes in the drum and 6 hooks can fasten the sprocket carrier and the pipe together.

 

Design of sled

The sled consists of a Ø73mm pulley from gym equipment (easy accessible), sliding gate cantilever track, a strong closed-loop stepper motor and worm gear.

Design of wirecutter

The idea behind this construction was to make a wirecutter that could be actuated by an electrical input.

In the end, it became a very effective solution. When the wirecutter is activated the blade will angled two time 45° to the wire, which will make the wire cut it self by pulling the wire with a force lower than 0.5kg.

 

The actuator is a 12V solonoid that gets 24V for few seconds, when the wirecutter is activated.

Design of wire inlet

The wire inlet is made out of two pillow block bearings, some roller skate bearings, Ø22 aluminium pipe, and the same Ø73 pulley wheels as for the sled.

Choice of frequency converter

Long story short… There are two types of frequency converters:
– Converters for pumps and fans
– Converters for conveyors, cranes or mills

 

The first type is more common, the second type is what we like, because it has a lot of nice features, as it is designed for demanding applications.

 

However, the important part is that the frequency converter has a “torque limitation”. This allows to limit the torque, which is propotional to the tension in the line.

 

It is very beneficial if the converter also allows closed-loop operation, because the torque accuracy becomes better in the very low end (0-20 kg). This is important for hanggliders that starts from a start trolley, as it begins to roll if the tension is more than 10-15 kg.

 

The “ATV61” from Schneider is build for pumps but still provides torque limitation. But the newer generation from Schneider “ATV600” build for pumps does not.

“Power limitation”, or the very common “current limitation” does not work.

ATV61 and ATV600 does not allow closed-loop operation.

 

The ATV71 and the newer generation ATV900 does both provide torque limitation and closed loop operation.

ATV320 does provide torque limitation but not closed-loop operation.

 

You just have to google the manual of the drive, and see if it provides torque limitation.

 

There are many brands producing frequency converters. Use the big brands as the algorithms in these provides the best performance, i.g. Schneider-Electric, Siemens, ABB, Danfoss, etc.

The frequency converters VLT FC301 and FC302 from Danfoss does also provide torque limitation and closed-loop operation.

 

The size of the converter should fit the motor and be able to provides sufficient current to generate the desired torque. See the table in “Design of motor”.

Design of battery

Converter circuit
Power circuit of a frequency converter: L1, L2 and L3 is the normal input. U, V and W are connected to the motor terminals. The battery should be connected through PA/+ and PC/-, which are the DC-terminals.

All industrial frequency converters are design for 480VAC plus 5% even though we only have 400VAC in Europe.

 

Inside the frequency converter the AC-voltage is rectified to DC-voltage. The DC-voltage will become 1.414 times the AC-voltage.

This means the battery pack should be designed to have a end-of-charge voltage of 710VDC.

 

The end-of-charge voltage of af lead acid battery is 14.2VDC.

Using 50 lead acid batteries in serial connection we get exactly 710VDC.

 

Two LED-drivers can be used to charge the battery pack. These should be connected through the rectifier, to protect the LED-drivers for reverse voltages. The first one connected to L1 and L2, the second one to L2 and L3.

 

The LED-drivers can be current controlled through two DIM-wires with a 0-10V signal which can be controlled by a PLC.

 

Two of these Meanwell XLG-240-L-AB LED-drivers are only capable of charging 48 leac acid batteries, but that is still sufficient. Other model are also avialiable, if you want more power or higher voltage (do not to go above 710VDC for longere periods).

 

Lead acid batteries are exhausting gasses, even though it is a GEL-battery. Therefore ventivation are needed: passive of active ventilation.

For 48 pcs. 12V 30Ah GEL batteries a hole of 200cm2 are required in the bottom and top of the battery enclosure according to EN50272-2 for passiv ventilation and boost charge, 25cm2 for float charge.

 

 

Safety precautions:

Working with and near high voltage installations shall only be done by professionals.

Be aware that 710VDC are very dangerous. Even though you think it is an isolated circuit, the reality can be different due to electric failures on any isolation.
To comply EN60204-1 isolation monitoring is mandatory. Read more here and here.

3D-drawing in Google SketchUp

Get the 3D-drawings right here.

 

The 3D-drawing is made in Google SketchUp.

 

Open the model for free by using Google SketchUp Free

Diagram