Patent Publication Number: US-11390366-B2

Title: Electronic control module for electrically assisted pedal-powered boat

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims benefit, under 35 U.S.C. § 119(e), of U.S. provisional application Ser. No. 62/966,759, filed on Jan. 28, 2020, which is incorporated herein in its entirety by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to a hybrid powertrain for boat or watercraft that combines a pedal-powered generator with a battery-powered electric motor. 
     BACKGROUND OF THE INVENTION 
     A multitude of pedal-powered watercraft (also referred to as water bikes, water-bicycles, and watercycles) are commercially available. Their main drawback is the relatively low power output capability of the operators. Unlike watercraft propelled by conventional combustion engines, pedal-powered watercraft are severely limited in power capability, which is typically less than 200 watts (around [¼] hp) per person on a continuous basis. A cyclist in good condition can generate around 200 watts at a preferred cadence of around 90-100 RPM. 
     There are also commercially available pedal-powered watercrafts that allow the use of an electric motor powered by a battery. However, these watercrafts do not use simultaneously both the human kinetic power and the battery power as in the case of known electrically assisted bicycles. 
     The main difficulty of a boat propulsion system is that it is difficult to effectively couple two driving forces that would have to accomplish the transmission of force on two different planes or axes unlike the electrically assisted bicycle. For example, on an electrically assisted bicycle at a speed of 25 km/h (15.5 miles/h), the wheel rotates typically at 250 RPM and the cyclist pedals at 60 RPM on average. It is therefore relatively easy to achieve a 3:1 overdrive. However, for a boat using an electric motor system the ratio required would be of about 40:1. 
     Most marine propellers use screw propellers with helical blades that rotate around an approximately horizontal axis defined by a propeller shaft. These screw propellers achieve great efficiency and ease of integration. However, these require high speeds of rotation and are unfortunately positioned at 90 degrees with respect to the axis of the pedal shaft. Mechanically, the construction of a system combining a propeller driven by electric propulsion motor and a mechanical pedaling system would substantially reduce the total efficiency of the system. For example, such 90 degrees positioning of the pedal with respect of the propeller typically reduces the efficiency by 17% while an overdrive system achieving 60 RPM at 2400 RPM typically reduces the efficiency by 15%. This would result in a loss of efficiency of 25% to 35%. 
     Also know is U.S. Pat. No. 6,855,016 (Jansen), which discloses a watercraft incorporating electrical power generation from human kinetic power, and electrical energy storage to enable amplification of human-power to propulsion power to achieve increased watercraft speeds. Control electronics enable operator-adjustable variable electronic gearing, and an assortment of torque vs. speed loading characteristics of the generator. 
     However, there is still a need in the field for an improved hybrid pedal powered and electrically assisted boat propeller system. 
     SUMMARY OF THE INVENTION 
     In order to address the above and other drawbacks, there is provided electronic control module for coupling a pedal mechanically powered electric generator and a battery to a motor controller of a watercraft propulsion motor, comprising: an electrical input operatively connected to the generator; a processor with a memory having an output operatively connected to the motor controller, said processor being operationally selectable by a user to one of multiple modes so that the processor being is configured to: in a first mode, combine power from the generator with power from the battery to power the motor; in a second mode, combine power from the generator with partial power from the battery to power the motor; and in a third mode, transfer power from the generator to charge the battery. 
     In embodiments, the control module is configured to determine a direction of rotation of the generator between a forward direction or a reverse direction; and to activate the motor in a same direction as the forward or reverse direction of the generator. 
     In embodiments, the control module comprises a comparator having inputs connected to electrical terminals of the generator and an output connected to an input of the motor controller for determining the direction of rotation of the generator. 
     In embodiments, a propeller assembly is operatively connectable to the electronic control module. 
     In embodiments, a pedal mechanism is operatively connectable to the propeller assembly. 
     According to the present invention, there is also provided a watercraft comprising: a mechanically powered generator; an electronic control module operationally connectable to the pedal powered generator; a battery operationally connectable to the electronic control module; a motor controller operationally connectable to the electronic control module; a propulsion motor operationally connectable to the motor controller for propelling the watercraft in forward or backward directions; wherein said processor is operationally selectable by a user to choose between one of multiple modes so that the processor is configured to: in a first mode, combine power from the generator with power from the to power the motor; in a second mode, combine power from the generator with partial power from the battery to power the motor; and in a third mode, transfer power from the generator to charge the battery. 
     In embodiments, the method comprises, by the electronic control module: determining the selected mode among the first, second and third modes; reading a current of the generator; comparing the current of the generator to a threshold value; if the current is above the threshold value then calculating a propulsion motor power command depending on the selected mode among the first, second and third modes; and transmitting the motor power command to the motor controller. 
     In embodiments, the method comprises, by the electronic control module: determining a direction of rotation of the generator between a forward direction or a reverse direction; activating the motor in a same direction as the forward or reverse direction of the generator. 
     In embodiments, the method comprises, in the first mode, combining up to 100% of available power of the generator with to up to 100% of available power of the battery to deliver up to 200% power to the motor. 
     In embodiments, the method comprises, in the second mode, combining up to a first percentage of available power of the generator with up to a second percentage of available power of the battery to deliver up to 100% of available power to the motor. 
     In embodiments, the first percentage of available power of the generator is up to 80% and the second percentage of available power of the battery is up to 20%. 
     In embodiments, the third mode transfers up 100% of available power of the generator to the battery. 
     Other objects, advantages and features of the present invention will become more apparent upon reading of the following non-restrictive description of specific embodiments thereof, given by way of examples only with reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a watercraft including a pedal mechanism an electric control module, generator, motor controller, battery and motor, according to an illustrative embodiment of the present invention; 
         FIG. 2  is a perspective view of a propeller assembly, according to an illustrative embodiment of the present invention; 
         FIG. 3  is a side view of a propeller assembly, according to another illustrative embodiment of the present invention; 
         FIG. 4  is a schematic block diagram of electric components used for controlling the propulsion of a watercraft, in accordance with an illustrative embodiment of the present invention; and 
         FIG. 5  is schematic block diagram of electric components for controlling the propulsion of a watercraft, in accordance with an illustrative embodiment of the present invention. 
         FIG. 6  is schematic block diagram illustrating various inputs and outputs of the electronic control module, in accordance with an illustrative embodiment of the present invention. 
         FIG. 7  is schematic flow diagram of a method for operating a system, according to an illustrative embodiment of the present invention. 
         FIG. 8  is a schematic diagram of operation of the system in a first mode, according to an illustrative embodiment of the present invention. 
         FIG. 9  is a schematic graphic of the maximum power and voltage of the propulsion motor with or without assistance from a generator, according to an illustrative embodiment of the present invention. 
         FIG. 10  is a schematic diagram of operation of the system in a second mode, according to an illustrative embodiment of the present invention. 
         FIG. 11  is a schematic diagram of operation of the system in a third mode, according to an illustrative embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     The present invention is illustrated in further details by the following non-limiting examples. 
     Referring to  FIG. 1 , there is shown a kayak or watercraft  10  with a seat  12  provided for the watercraft operator. Propulsion is accomplished via a centrally mounted propulsion unit  14 . The propulsion unit  14  includes a foot pedal mechanism  16 , similar to that of common bicycles, having a pedal  18  with a crank arm  20  that is operatively connected to a spindle  22  and chain wheel  24  about which is mounted a chain  26 . The foot pedal mechanism  16  is operatively coupled to an electric generator  28  that is mechanically powered via the chain  26 . It is also possible to have the pedal arms connected directly to the generator without the use of chain wheel and chain with proper generator winding configuration. The watercraft operator rotates the electric generator  28  by pedaling via the pedal  18 . Mechanical power (i.e. kinetic energy) of the watercraft operator&#39;s pedaling action is converted to electrical power via the electric generator  28 . Although a foot pedal  18  is shown, the electric generator  28  may instead be operatively connected to hand grips and positioned to utilize upper body motion, rather than leg motion. The electric generator  28  may be a brushless DC (BLDC) motor, such as for example having rating of 48 Volts and 500 Watts, but any other suitable generator may be used instead as persons skilled in the art will understand. A battery  44  is shown connected to the propulsion unit  14 . 
     Referring now to  FIG. 2 , in addition to  FIG. 1 , the propulsion unit  14  also includes a propeller assembly  30  having an electric motor  32  operatively connected to a screw propeller  34  with helical blades  36 . The electric motor  32  is shown mounted on a pivoting shaft  38  at one end thereof extending in a generally central position of the watercraft  10 . The propeller assembly  30  may alternatively be fixedly mounted to the watercraft instead of being pivotably mounted and a separate rudder (not shown) may be used to direct the watercraft. A control console  40  is mounted on the other end of the pivoting shaft  38 . A handle  42  is connected to the control console  40  for directing the screw propeller  34  towards different directions via the pivoting shaft  38 . 
     Referring now to  FIG. 3 , there is shown an alternative propulsion unit for a kayak or watercraft that is similar to the one shown in  FIG. 1 . The propulsion unit includes pedals  18  with a crank arm  20  that is directly connected to an electric generator  28 . The watercraft operator rotates the electric generator  28  by pedaling via pedals  18 . Mechanical power (i.e. kinetic energy) of the watercraft operator&#39;s pedaling action is converted to electrical power via the electric generator  28 . In this embodiment, the electrical generator  28  is slidably mounted on a horizontally adjustable shaft  21  via a locking mechanism  23  for locking in position the shaft  21  with respect to a vertical shaft  25 . The adjustable shaft  21  is especially useful in watercrafts or kayaks where the seats are not adjustable horizontally and allow for operators with different leg lengths to comfortably adjust the pedal distance. Similarly, as in  FIG. 1 , the propulsion unit also includes a propeller assembly having an electric motor  32  operatively connected to a screw propeller  34  with helical blades  36 . A battery  44  is electrically connected to the propulsion unit. A motor controller  48  is shown above shaft  38  that links the motor controller  48  to the electric motor  32 . 
     Referring now to  FIG. 4 , in addition to  FIGS. 1 to 3 , there is shown some of the electric components of the propeller assembly  30  that are used for controlling the propulsion of the watercraft  10 . As can be seen, the electric generator  28  is not mechanically connected to the motor  32 , which is advantageous over know prior art watercraft propeller systems described in the background section where it was explained that it is difficult to effectively couple two driving forces that would have to accomplish the transmission of force on two different planes or axes. 
     A battery  44 , such as a lithium oxide battery or any suitable kind of batteries, is operatively electrically connected to the electric generator  28  for storing the power generated by the pedaling action of the foot pedal mechanism  16 . 
     Referring back to  FIGS. 3 and 4 , an electric control module  46  is shown operatively connected to the electric generator  28  and a motor controller  48  is shown operatively connected to the electric motor  32 . 
     Referring now to  FIG. 5 , in addition to  FIGS. 1 to 4 , there is shown a more detailed schematic diagram of components of a propulsion system, according to a preferred embodiment. The electric control module  46  is shown operatively connected to the electric generator  28  with pedals  18  and crank arms  20 . The electronic module  46  is also operatively connected to the motor controller  48 , which is shown connected to the electric motor  32 . The electronic control module  46  includes a comparator LM 1  that has its two inputs respectively connected to the generator  28  at terminals  28 . 1  and  28 . 2 . The output of the comparator LM 1  is connected to an input of the motor controller  48 . The electronic control module  46  includes a rectifying diode bridge D for converting AC power from the generator  28  to DC power for powering the battery  44 , and motor  32 . The diode bridge D has four diodes with two AC terminals D 1 , D 2  respectively connected across terminals  28 . 1  and  28 . 2  of the generator  28 . The diode bridge D has a positive terminal D 3  connected to a positive terminal of the motor controller  48  and to a positive terminal  44 . 1  of battery  44 . The diode bridge D has a negative terminal D 4  connected to a first input ( 14 ,  15 ,  16 ) of an integrated circuit U 4  (INA250A1PWR), which includes a processor with a memory. A second input ( 1 ,  2 ,  3 ) of the integrated circuit U 4  is connected to a negative terminal  44 . 2  of the battery  44  and to a negative terminal of the motor controller  48 . An output  9  of the integrated circuit U 4  is connected to an input of the motor controller  48  for allowing a selection of the power assistance level that is controlled by the user to provide power from the generator  28  to the motor  42 . 
     Referring now to  FIG. 6 , in addition to  FIGS. 1 to 5 , there is shown the different inputs and outputs of the electric control module  46 . Inputs include generator power from electric generator  28  and power level adjustment. Outputs include battery power to the battery  44 , propulsion motor controller power to the motor controller  48 , motor assistance control, motor forward/reverse control and generator power information. 
     Referring now to  FIG. 7 , in addition to  FIGS. 1 to 6 , there is shown a schematic flow diagram of a method for operating a system including the electronic control module  46  for coupling the pedal powered generator  28  to the motor controller  48  of the watercraft motor  32 , according to a preferred embodiment. The method begins operation by reading a current from generator  28  at step  70 . A filtering of the current is performed at step  72 . The filtered current of the generator  28  is compared against a threshold value, for example 1 A, at step  74 . If the filtered current of the generator  28  is lower than 1 A then the propulsion motor  32  is stopped at step  76 . If the current of the generator is greater than 1 A, then the method continues by calculating the propulsion motor power command sent by the electronic control module  46  to the motor controller  48  at step  78 . The calculation of the propulsion motor power command is determined according to the selection of assistance mode at step  80  that is used to calculate the motor/generator ratio at step  82 . The selection of assistance mode at step  80  includes the selection of: 1. High motor power mode; or 2. Increase autonomy mode; or 3. Battery recharge mode. Another input parameter for calculating the propulsion motor power command involves receiving a value of the generator increase bus DC voltage at step  84 . The propulsion motor power command obtained at step  78  is then compared with a general direction at step  86 . If the motor power command corresponds to a forward direction then the motor controller  48  activates the propulsion motor  32  to forward at step  88 . If the motor power command corresponds to a reverse direction then the motor controller  48  activates the propulsion motor  32  to reverse at step  90 . 
     The power provided by the generator  28  to the motor  32  can be calculated according to the following formula:
 
 P   motor   =P   Generator   *A  
 
where P motor  is the power of motor propulsion in Watts (W).
 
     P Generator  is the power generated by the pedaling user in Watts (W) A is the assistance factor, which may be for example from 0 to 300%. 
     The energy provided by the generator  28  to the battery  44  can be calculated according to the following formula:
 
 E   Battery   =E   Generator   −E   Motor  
 
where E Battery  is the energy of the battery  44 , E Generator  is the energy of the generator  28  and E Motor  is the energy of the motor  32 , in Watts-hour (Wh).
 
     The power of the generator  28  is calculated according to the following formula:
 
 P   Generator =0 if RPM Generator &lt;RPM Minimum  
 
where RPM Generator  is the rotation per minute (rpm) of the generator  28 , and RPM Minimum  is the minimum rotation per minute (rpm) of the generator  28  for producing energy.
 
     The maximum power provided by to the motor  32  by the generator  28  can be calculated according to the following formula:
 
MaxP Motor   =I   Motor *( VOC   Battery   +R   INT *( I   Generator   −I   Motor ))
 
where MaXP motor  is the maximum power available for the propulsion motor  32  in Watts (W), I Motor  is the current of the motor  32  in Amps (A), VOC Battery  is the voltage charge of the battery  44  in Volts (V), R INT  is the internal resistance of the battery  44  in Ohms (Ω), I Generator  is the current of the generator  28  in Amps (A).
 
     The direction of rotation of the motor  32  is in the same direction as the direction of rotation of the generator  28 , which is determined by the electronic control module ( 46 ) by means of the comparator (LM 1 ). 
     Referring to  FIG. 8 , in addition to  FIGS. 1 to 7 , there is shown a schematic diagram of operation of the system in an Assistance Mode  1 : “High motor power” where both the generator  28  and battery  44  provide 100% of their available power to the propulsion motor  32  to achieve 200% of available power. 
     Referring to  FIG. 9 , in addition to  FIGS. 1 to 8 , there is shown a schematic graphic of the maximum power MaXP Motor  provided by to the motor  32  and the voltage of the battery  44  with no input power provided by the generator  28  to achieve a low power level LPL and low voltage level LVL, which is contrasted with the input power provided by the generator  28  to achieve a high power level HPL and high voltage level HVL. 
     Referring to  FIG. 10 , in addition to  FIGS. 1 to 9 , there is shown a schematic diagram of operation of the system in an Assistance Mode  2 : “Increase Autonomy” where the generator  28  provides 80% of the power and the battery  44  provides 20% of the power to achieve 100% of available power to the propulsion motor  32 . 
     Referring to  FIG. 11 , in addition to  FIGS. 1 to 10 , there is shown a schematic diagram of operation of the system in an Assistance Mode  3 : “Battery recharge” where the generator  28  provides 100% of the power and the battery  44  receives 100% of the power, while the propulsion motor  32  receives 0% of the power. 
     In embodiments, the system according to the present invention combines nautical electric propulsion from the electric motor  32  with that of a human being via the pedal assembly  16  and electric generator  28 . This makes it possible to add the human force to the electric power. For example, 500 Watts of electric propulsion+250 Watts of human power=750 Watts of total power. 
     In embodiments, the system according to the present invention optimizes the pedal&#39;s speed and effort to adapt to different users with different physical conditions. 
     In embodiments, the system of the present invention effectively allows for the combination of electric boat propulsion with human propulsion effort. 
     In embodiments, the system of the present invention advantageously eliminates the need for an extensive mechanical overdrive. 
     In embodiments, the system of the present invention allows an electrical connection only between the electrical components. It thereby enables ease of integration. 
     In embodiments, the system of the present invention is advantageously modular. The electric propulsion module can be used without the generator and with almost any type of battery. 
     In embodiments, the system of the present invention allows for several choices of techniques for using the system:
         Combined mode Human power+electric=Faster.   Generator mode: Allows charging the battery.   Battery Only Mode: No need to pedal       

     Forward and reverse motion can be accomplished by reversing the pedals rotation or by using the forward or reverse option on the display of the control console  40  that is operatively connected to the electric control module  46 .
         Only Human Mode: No need for battery power.       

     The electronic control module  46  allows among other things to have different levels of electrical assistance. 
     The scope of the claims should not be limited by the preferred embodiments set forth in the examples, but should be given the broadest interpretation consistent with the description as a whole.