Wave ball working principle

时间:2014-08-15 15:23:32来源: 作者: 点击: 0次

 Despite its round and simple appearance, the Wave Ball is a product of high level technology. Several sensors combined to a powerful software/hardware allow the ball to produce and increase the waves with a full control on the frequency and the amplitude.

Wave creation principle

Basis

The Wave Ball is the application result of three physical working principles :

  • Archimedes principle: wave ball is a floating sphere placed in the pool.
  • Inertia principle: a heavy plate (moving load) is moving up and down inside the ball shell. As the ball is placed in the water, the shell is moving up and down around the heavy plate which is not moving thanks to inertia principle.
  • Resonance principle: As the ball is working at one of the resonance frequency of the pool, the energy given to the pool is kept in the pool thanks to the freeboards. Each time the ball transmit its energy to the pool, the waves are becoming bigger and bigger.

Each wave is characterized thanks to several parameters such as amplitude (or height), wave length (peak to peak length) and frequency.

Pic 1 and fig 1: Characteristics of waves

Pic 1 and fig 1: Characteristics of waves.

 

Wave Creation and control

Thanks to the upwards thrust created by the ball, a first wave is spread in the pool (figure 2). Once reflected against the wall of the pool (figure 3), the wave comes back to the ball where it will be amplified (figure 4). A computer system computes the right impulsion time in order to increase (or decrease) the waves.

Some small waves are created by the Wave Ball

Fig 2 : Some small waves are created by the Wave Ball.

The small waves are spread to the walls of the pool

Fig 3 : The small waves are spread to the walls of the pool.

The waves are reflected and amplified each time they come back to the ball.

Fig 4 : The waves are reflected and amplified each time they come back to the ball.

Thanks to its electronic, the wave ball is able to compute the exact moment when the wave will be back from the wall and to predict when a pulse has to be given. The wave motion is then reinforced at each time a wave comes back to the ball. The amplitude will then grow until it reachs the one desired (fig 4).

Fig 5: Wave Ball behavior

Fig 5: Wave Ball behavior

The principle is the same as when you play on the swing and if someone is pushing you. If the person pushes you at the right moment, the amplitude of the movement will increase, even if the force with which he is pushing is weak. At the opposite, if he does not push at the right moment, if he is a little bit off the phase, the movement will stop growing and then decrease.

Wave Amplitude control mechanism

The more the Wave Ball transmits its energy to the water, the more the height of the wave increases. So, if we want to control the amplitude of the waves, we have to control the energy that is transferred from the Wave Ball to the water.

The transfer of energy is possible, only if the movement of the ball is shifted from the movement of the wave. The Wave Ball, to be efficient, has to anticipate its movement against the one of the wave. The shift between the Wave Ball movement and the wave movement is called the phase difference (figure 11). It is measured in degrees (°). The ball can give more or less energy by adapting the phase difference between its movement and the wave.

Figure 6: Wave mechanism

Figure 6: Wave mechanism.

Stationary waves Amplitude control

As the waves motion is regular, the Wave Ball can determine with accuracy the amplitude of the wave and the phase difference between its own motion and the one of the wave. The Wave Ball can then adapt this phase difference in order to reduce the amplitude difference between the one measured and the one requested and thus keep the waves at a fixed amplitude.

Non stationary waves Amplitude control

As the waves motion is not regular, the amplitude and the phase difference vary rapidly. Thus, it is not possible to control with accuracy the amplitude of the waves. The control enables to get an average of stronger or smaller waves.

Wave Ball and electrical equipment description

The system can be divided into two fundamental units which are the floating ball in the pool and the control & electrical equipment of the ball in the technical room.

Ball composition

Figure 7: Wave Ball composition

Figure 7: Wave Ball composition.

  1. The moving load :  the vertical movements of this load puts the ball in action. This load is moved by a rod-crank system connected to motor-reduction gear.
  2. The motor-reduction unit : used to put the moving load in motion. The motor is an asynchronous 12V AC motor.
  3. Synchronization sensors : One principal sensor and one backup sensor, used for motor regulation purpose.
  4. Water sensor : used for the detection of water in the ball
  5. CB50 box : used for sensor acquisition (water and synchronization sensors) and transmission to the electrical cabinet (modulation/demodulation signal) . Contains  the accelerometer for wave frequency and amplitude control purpose.
  6. Umbilical cable : the electrical power needed is supplied by a cable coming from the electrical equipment.

Control and electrical equipment description.

Technical working principle

Figure 8: Wave Ball hardware architecture

Figure 8: Wave Ball hardware architecture

The working orders travel on the CAN bus. The CAN bus is a 4 wires bus (2 wires for 12 VDC power supply, 2 wires for data transfer).  The CAN bus has been chosen for its high reliability in the electro magnetically perturbed areas (like in cars), the long cable distance allowed (maximum 500 m with 125 Kb flow rate) and its software controls.

A monophase safety transformer provides the power supply. This transformer is the same for all the range of Wave Ball.

The frequency converter is driven by the CAN card and supplies the 3 phases to the power safety transformer.  The size of inverter and power transformer depends on the wave ball size.

The data to communicate between the ball and the electrical box are modulated on 2 of the 3 ball cable power phases.

The CAN card

Each device has its own CAN card, which is a multi-interface between the CAN and the other communication channels.

  1. CAN card for the inverter (RS-485)
  2. CAN card for the RCU (TTL)
  3. CAN card for the PowerData card (TTL)
  4. CAN card for the MIO card (TTL)
  5. CAN card for the PC (RS-232)

The use of several CAN cards allows the devices to communicate each other throughout the CAN bus.

The PowerData card

The PowerData is a modem (modulator-demodulator) card, which is used in pair: the first one placed in the Wave Ball (in the CB50 box), the second one in the electrical cabinet close to the transformer (in the PowerData box).

The PowerData card is supplied either from the CAN card (transformer side) or from the CB50 card (ball side).

The MIO card

The MIO (Module Input Output) is an interface with an external control – command device.  It has 16 configurable inputs/outputs.

Inputs can be used, among other things, to start the ball from an external device (push button, PLC, ...). The outputs can be used, among other things, to indicate the ball status to an external device (Light, PLC, ...).

See CB50 software manual for available functions.

The RCU card

The RCU (Remote Control Unit) card contains the human interface functions (keyboard inputs, display) and the memory .  There are two memory zones: EEPROM and RAM.  The active data are in the RAM, the data to save are in the EEPROM.

The RCU card is multi-language (English and French are available).

The CB50 card

The CB50 makes the acquisition of the data coming from the ball sensors :

  • Accelerometers : measure the wave amplitude;
  • Main zero : measures the wave ball frequency (crank rotation speed);
  • Backup zero : verifies the rotation direction;
  • Shell water sensor : detects the abnormal presence of water in the shell bottom;
  • Lock water sensor : detects the abnormal presence of water in the shell lock (for removable cable, only available on W105F(L), W130F(L) and W150F(L) shell);

These sensors information are sent to the bus CAN via the powerdata card.

Components

All cards described above are protected in a box and, depending of the function, combined with another card.

Figure 9: RCU box

Figure 9: RCU box

This box called RCU for Remote Control Unit is used to command the wave generator (human interface). The user is able to select different kind of waves, to start and stop the Wave Ball.

The RCU box is composed by a display, the wave buttons, the emergency stop, the safety key and the navigation keys.

This box includes a RCU card and a CAN card. The wave regulation (control) is taken in order by the RCU card. The actions to the ball are given to the inverter throughout the CAN bus.

Figure 10: CAN box

Figure 10: CAN box

This box includes a CAN card configured in RS485 mode. It is the communication device between the CAN bus and the frequency converter.

Figure 11: Power Data box

Figure 11: Power Data box

This box includes a CAN card and a PowerData card. It is the communication device between the CAN bus and the wave ball.

Figure 12: MIO box

Figure 12: MIO box

This box includes a CAN card and a MIO card. It is the communication device between CAN bus and an external control command device. This box is associated with a terminal which allows the connection with external devices.

Figure 13: frequency converter

Figure 13: frequency converter

This unit supplies the power to the motor via the transformer and control its speed by changing the electrical frequency (0 ~ 60 Hz). It is driven by the RCU via the CAN bus.

Figure 14: transformator

Figure 14: transformator

The 3 phases transformer converts the output voltage of the frequency converter to the allowed safety output voltage in the pool (12V AC). Two of the three power phases are used for data transfer.

Figure 15: CB50 box

Figure 15: CB50 box

This box includes a CB50 card and a powerdata card. The sensors data are sent to the electrical cabinet thanks to this box.

------分隔线----------------------------