Cadence control method for a hybrid drive using a power splitter applicable to electric bicycles

Abstract

The present invention relates to a cadence control method for a hybrid drive applicable to electric bicycles, the hybrid drive comprising a muscle power input (PM) and an electric motor (eM1), both being connected to a power-split gear (PS), the power output (LS2) of which is mechanically connected to a wheel (RM). The hybrid drive is equipped with a control device (HMI) that allows the user to select a preset cadence (Wc(prog)) and said control method acts on the motor (eM1), thereby increasing or decreasing its power to slow down or accelerate the pedalling cadence (Wc), keeping its value close to the preset cadence (Wc(prog)). This method applies to both pedal-driven vehicles with power-split hybridisation with a single electric machine, and vehicles equipped with an e-CVT system with parallel hybridisation at the output, in which the cyclist also selects a level of assistance.

Description

[0001] Cadence control procedure for a hybrid power divider drive applicable to electric bicycles

[0002] TECHNICAL SECTOR

[0003] The present invention belongs to the field of technology relating to drive mechanisms for hybrid systems in vehicles, more particularly to the control system of these hybrid drives in electric bicycles, known as e-bikes.

[0004] BACKGROUND OF THE INVENTION

[0005] In the field of e-bikes, the following hybridization systems are widely known:

[0006] • Parallel hybridization: where an electric motor adds torque to boost power output. This configuration is the one most commonly used in e-bikes on the market.

[0007] • Power-split hybridization: where an electric machine—motor / generator—adds / subtracts speed from another power source, at least partially muscular. In this case, an overlapping gear—also called a power-split mechanism, speed coupling, or simply "power-split"—is used, such as a planetary gear. This transmission has a first member, where at least the muscular power of a cyclist is received, either directly from the crankset or through any interposed transmission mechanism, such as a chain and sprocket; a second member, where the power from the electric machine is received; and a third transmission member, where the power output is the sum of the previous two through speed coupling, since the corresponding torques between any two of the three members always remain proportional.In the e-bike market, its application in bicycles with a single electric motor is not well known, but there are many patents that propose its use, such as US9758212B2 from BOSCH.

[0008] • e-CVT systems: These systems utilize two electric motors / generators, or electric machines, one connected via a power-split system and the other connected in parallel. Since one provides additional speed and the other additional torque, the result is electric assistance that covers a wide range of gear ratios, effectively functioning as a gearbox. This is well-established in the automotive industry, with Toyota's hybrid range being the most representative example. This type of hybridization can be implemented in at least two different ways: with the electric machine connected in parallel either at the input alongside the engine's power, or with the electric machine connected in parallel at the output. This output can be the power-split output or a mechanical connection to at least one of the vehicle's wheels. We refer to these two types of e-CVT systems as having parallel input hybridization and having parallel output hybridization.

[0009] In the cycling market, for now, we only have the E2 Drives system — WO2016034574A1, US11383791B2 and US2022274670A1 — marketed by Decathlon under the OWURU brand, which would be an e-CVT with parallel hybridization at the entrance.

[0010] Control systems for parallel hybrid systems are widely known. Control systems for e-CVT systems are extensively documented, and it is worth mentioning, in addition to the aforementioned E2 Drives documents, ZF patents DE102022213149B3 and DE102023203892B3.

[0011] The present invention deals primarily with pure power-split hybrid systems, that is, single-motor electric systems, where control systems are less developed and documented, as these systems have not yet been implemented in a commercially viable mechanical product. This is mainly because muscle power is delivered with very pronounced torque peaks that alternate with dead spots during pedaling, which would necessitate the use of a very large electric motor or a mechanical reduction ratio too high for conventional gear train or epicyclic systems, which are suitable for a bicycle that should be lightweight and compact.

[0012] In power-split hybrid systems applied to e-bikes, there are two power inputs, one fast and one slow, and one power output (also slow). The power divider—speed coupling—combines the speeds of both inputs, superimposing their movements and resulting in an output that sums both contributions according to the gear ratios of each input relative to the output. Thus, if the fast input has a 50:1 reduction, and the slow input a 50 / 49:1 reduction (approximately 1.02:1), when the fast input is rotating at 2000 rpm, its contribution to the output will be 2000 / 50 = 40 rpm; and if the slow input is rotating at 80 rpm, its contribution will be 80 / 1.02 = 78.4 rpm; and therefore the output will rotate at 40 rpm + 78.4 rpm = 118.4 rpm. The park has to contribute each input will be equal to the resistive torque at the output affected by the transmission ratio of each input.In the previous case, if the resistive torque were 25 Nm, at the slow input a torque of 25 / 1.02 = 24.50 Nm would have to be applied, and at the fast input 25 / 50 = 0.5 Nm

[0013] Regarding control systems applicable to power-split hybrids, the first patent is the aforementioned US9758212B2, which briefly defines a control system that measures the revolutions per minute (RPM) of either the slow input shaft—the first transmission member—or the output shaft—the third transmission member—since the motor's RPM is assumed to be known, thus automatically determining the RPM of the other component. A speed sensor is also used on the wheel—downstream of a bicycle gear shift. This control system would be responsible for both activating an actuator that performs the mechanical gear changes on the bicycle and establishing the motor's RPM. The patent does not elaborate further on the possible control algorithms.

[0014] Then there are the patents that refer to control systems in drives that provide a continuously variable transmission ratio electronically (or e-CVT, “electronic continuous variable transmission”). Related to these are the patents of the company E2 Drives (US2015122565A1, US10479447B2, US11091225B2, US11383791 B2, US11772740B2, US20220274670A1, EP3932794A1), which describe drive systems of this type applicable to electric bicycles, and their control system. e-CVTs can be implemented by combining two electric motors, one coupled in speed (using a power divider), and the other in torque (conventional parallel hybridization). Applying more or less power to the motor coupled in speed results in a higher or lower final speed, respectively. Applying more or less power to the coupled motor results in a higher or lower final torque, respectively.Therefore, a distribution in which the assistance power is constant, and the ratio between the two varies, provides an e-CVT, in which the level of assistance can be selected. In the E2 Drives patents, given the mechanical implementation of the drive, a system is described in which, based on the angular position of the human power input and that of the speed-coupled motor, the speed of the latter is controlled proportionally to the speed of the slow (human) input. It is thus a speed control system for the speed-coupled motor, with the motor speed setpoint being proportional to the input. The torque-coupled motor is controlled by torque according to the selected assistance level and the torque being handled by the first motor. There are also patents for systems of this same type filed by the company ZF (DE102022213149B3 and DE102023203892B3).The first claim also includes a control system applicable to a power-split or speed-coupled hybrid system. In this system, the output speed of the speed-coupled drive is measured, and the motor speed is set according to a predetermined gear ratio between pedaling and drive output. The torque-coupled motor control is set according to an additional, also predetermined, torque. In this way, this system would function as a drive with a finite number of discrete speeds instead of a continuously variable gear ratio. In patent DE102023203892B3, the drive output speed is measured, and a target cyclist cadence is determined, calculated from a predetermined ratio between input and output speeds.According to this target cadence, to achieve a specific gear ratio on the bicycle, the speed-coupled motor is controlled. This is essentially the same approach as in the E2 Drives patents, but focusing on the output instead of the input. Subsequent claims add algorithms to prevent slippage of the speed-coupled motor when the torque applied by the cyclist exceeds the motor's capacity. They also add a second torque-coupled motor to create an e-CVT, as well as a complete drive system based on a specific mechanical design and an electric bicycle incorporating said drive system.

[0015] Patent DE102023203892B3 has been cited by the Spanish Patent and Trademark Office (OEPM) as the most relevant document — D01 — in the State of the Art Report for Spanish application ES202530027, publication number ES3034822A1, the priority document for this international application. The report states:

[0016] “The control procedure of document D01 works in such a way that the first electric machine introduces more or less power into the power-split gear, generating a resistive torque on the input of muscular power, thus maintaining a value close to a pre-programmed target cadence.”

[0017] However, the aforementioned patent states that, once the output speed is measured, the system determines the cyclist's cadence to achieve a predetermined relationship between cadence and output speed. According to the Willis equation, a kinematic equation that, in this case, relates output speed to cadence and the electric motor's input speed, the system calculates the motor speed required for the cadence to meet this predetermined relationship. Therefore, the system does not respond to achieve a user-selected cadence, but rather to ensure a pre-programmed kinematic relationship through a strategic function that links the vehicle's speed to a target gear ratio. The control system is designed to maintain an algorithmically determined gear ratio, while the cyclist's cadence is a variable derived from this ratio and the bicycle's speed.

[0018] With regard to mechanical drives that provide high-speed coupling and a high transmission ratio between the fast input and output, it is worth mentioning WO2024170938A1 and the Spanish patent application P202430744, both filed by Quaternion Ingeniería de Sistemas Electromecánicos SL

[0019] If we consider only those e-bikes that are assisted by a single electric motor, for now, only parallel hybrid e-bikes exist on the market; however, these present several problems to be solved:

[0020] • They need a torque sensor, which, in addition to increasing the cost, generates delays both in starting and stopping the push when the cyclist suddenly stops pedaling in the face of a potential obstacle; thus becoming a critical component in terms of perceived quality of use.

[0021] • When there is a change in pedaling conditions, such as a change in the gradient faced by the cyclist, they have two different control systems to act on: the mechanical gear shift, and the electric assistance level, the latter being the one that very often ends up being used to the detriment of a better cycling experience, as well as penalizing the autonomy and useful life of the chain, chainring and sprockets.

[0022] SUMMARY OF THE INVENTION

[0023] The current invention applies both to pedal-powered vehicles with a single electric motor and to pedal-powered vehicles equipped with an e-CVT system with parallel hybridization at the output.

[0024] By proposing a power-split hybrid system in both cases, a pedal torque sensor is unnecessary, as torque is always proportional to the phase intensity of the corresponding electric motor. Therefore, only cadence needs to be measured, which is much simpler and cheaper than a torque sensor.

[0025] The proposed control system aims to achieve an interaction between the cyclist and the electric assist that provides a user experience as close as possible to that of riding a bicycle by hand. The goal is for the level of electric assistance to be unconsciously controlled by the cyclist at all times, not through predetermined ratios, but by adapting as naturally as possible to both the terrain and the pace and effort exerted by the cyclist.

[0026] In the case of the power-split hybrid pedal vehicle with a single electric motor, the control system will apply both to drives located upstream of the pedal vehicle's gear change — in the pedal area, commonly referred to as central motors — and to drives located downstream of the gear change — for example, included in the rear wheel of the bicycle in the case of hub motors —.

[0027] The present invention therefore proposes a cadence control procedure for a hybrid power divider drive, applicable to electric bicycles, comprising at least:

[0028] • a power-split gear with a first transmission member — hereafter referred to as slow input — , a second transmission member — hereafter referred to as fast input — , and a third transmission member — hereafter referred to as slow output — ; wherein the slow input is mechanically and exclusively connected to the muscle power input without receiving any other power input;

[0029] • a first electrical machine mechanically connected to said fast input, and electrically to a controller, to a source of electrical power, or to a control device or human-machine interface;

[0030] • means of measuring pedaling cadence;

[0031] where said control device or human-machine interface allows the user to choose a cadence they would like to maintain, which we will call programmed cadence;

[0032] and where said control procedure is characterized by the fact that it acts in such a way that the first electric machine introduces more or less power into the power-split gear, generating a greater or lesser resistive moment on the human power input, so that the pedaling cadence will be slowed down or accelerated, thus managing to maintain, within a wide range of operating conditions, a value close to the programmed cadence.

[0033] In the control procedure, the programmed cadence will not always be maintained. Internally, the control system operates according to a setpoint cadence, which is the cadence the control system attempts to maintain through the action of the electric motor. This will generally be the same as the programmed cadence, but it may temporarily differ. This could be due to the cyclist intentionally stopping pedaling, in which case the motor should stop immediately; or it could be that the motor's maximum power has been reached, or that the electric assist system has exceeded one of its limits. These limits may include reaching the motor's maximum revolutions per minute, the maximum permissible current, or a temperature that could compromise the system.In such cases, the control system must establish a new setpoint rate, higher than the programmed one, and / or reduce the rotational speed of the first electric machine, decreasing the load on the entire electrical system.

[0034] BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1.- Represents the drive system of a pedal-powered vehicle with a hybrid power-split system and a single electric motor, in a mid-motor configuration. It has an electric drive, consisting of the battery, motor controller, the first electric motor (eM1), and a human-machine interface (HMI). It also has a power-split gear system (PS), with a first slow-input transmission member (LS1) to which the muscle power input (PM), represented by a pedal mechanism with a cadence sensor (CS), is connected; a second fast-input transmission member (HS1), to which the first electric motor is connected; and a third slow-output transmission member (LS2), mechanically connected via a gear shift (GS) to a drive wheel (RM) equipped with a speed sensor (SS).

[0036] Figure 2.- Represents the drive system of a pedal vehicle with power-split hybridization and a single electric motor, in a hub motor configuration. The muscle power input (PM) passes through the gearbox (GS) before entering the powersplit (PS) via the slow input (LS1). The slow output (LS2) is mechanically coupled to at least one wheel of the vehicle. Figure 3.- Represents the drive system of a pedal vehicle with an e-CVT and parallel hybridization at the output. The connection between the slow input (LS1) and the muscle power input (PM) can be made directly by the bottom bracket, or by any other transmission system, such as a sprocket receiving all the muscle power in a rear hub motor. The slow output (LS2) is shown mechanically connected to the drive wheel (RM), either by a chain and sprocket, pulleys and belt, etc.— in the case of a central motor — , or directly coupled to the wheel hub — in the case of a hub motor — . The second electric machine (eM2) is mechanically coupled by means of a speed reduction mechanism (RED) in parallel, either to the slow output (LS2) of the power-split gear (PS), or to at least one wheel of the vehicle. The electronic controller (control) is of the dual type capable of controlling both electric machines — two controllers with communication between them — .

[0037] Figure 4.- Flowchart of the control procedure of a power-split hybrid vehicle with a single electric machine, corresponding to Figures 1 and 2. The flow of the described procedure is represented, identifying its 12 main blocks.

[0038] Figure 5.- Flowchart of the vehicle control procedure with e-CVT corresponding to Figure 3. The flow of the described procedure is represented, identifying its 19 main blocks.

[0039] Figure 6.- For the case of a vehicle corresponding to Figures 1 or 2, a temporal evolution of the cyclist's cadence (Wc) and the set cadence value (Wc(con)) is represented in descending order; the value of the determined error (e); the evolution of the rotational speed of the first electric machine (Wem1); and the evolution of the rotational speed (Wr) of the driving wheel (RM).

[0040] Figure 7.- Graph according to time of various variables for the case of a vehicle corresponding to Figures 1 or 2, in the case in which the critical state (C3) is reached.

[0041] Figure 8.- Graph according to time of various variables in the case in which the critical state (C1) is reached.

[0042] PREFERRED EMBODIMENT OF THE INVENTION

[0043] A preferred embodiment of the present invention consists of a control procedure for a power-split hybrid pedal vehicle with a single electric motor and mechanical gear-shifting system: For said vehicle, which is also subject to a regulation that imposes a maximum speed limit while maintaining electric assistance, the vehicle will necessarily have a speed sensor (SS), and preferably its control procedure would comprise the following steps:

[0044] (I) Determine the error (e) as the difference between the measured cadence of the cyclist (Wc) and the set cadence (Wc(con));

[0045] (II) Determine a set speed (Wem1(con)) for the first electric machine (eM1) according to a function of the instantaneous value of the error (e) and / or the historical value of said error (e): Wem1(con)) = F(e(r), T=0, r=t);

[0046] (III) Measure the speed of the bicycle (Vb) using the speed sensor (SS);

[0047] (IV) Detect a first critical state (C1) consisting of the setpoint speed (Wem1(con)) determined in (II) being higher than a value corresponding to the maximum speed of the first electric machine determined by its manufacturer (Weml(max));

[0048] (V) Reduce the setpoint speed of the first electric machine (Wem1(con)) and / or temporarily increase the setpoint rate (Wc(con)) to get out of the critical state (C1).

[0049] In this case, the system's ability to limit the cyclist's cadence to the programmed cadence disappears. The cyclist will naturally shift to a higher gear, which will slow their cadence (Wc) again, causing the set speed of the first electric motor (Wem1(con)) to decrease, moving away from the critical state (C1).

[0050] (VI) Detect a second critical state (C2) in which the resistive moment (Cerní) on the first electric machine (eM1) causes the electric current (Iem1) to reach a critical value, or the power maintained for a certain time to be above a legal limit or induce critical temperatures in the system.

[0051] (Vil) Modify the setpoint speed of the first electric machine (Wem1(con)) and / or temporarily the setpoint rate (Wc(con)) to avoid the critical state (C2).

[0052] Again, the system's ability to limit the rider's cadence (Wc) to the programmed cadence (Wc(prog)) disappears, the rider's cadence (Wc) increases, and the power (Pem1) required from the first electric motor (eM1) decreases. At this point, the rider's intervention by shifting gears (GS) to a higher gear slows their cadence (Wc) while simultaneously decreasing the electric power, and thus the level of assistance.

[0053] (VIII) Detect a third critical state (C3), consisting of the bicycle speed (Vb) being higher than the maximum allowed under electric assistance conditions (e.g.

[0054] 25 km / h Europe or 32 km / h USA),

[0055] (IX) Modify the set speed of the first electric machine (Wembl(con)) to get out of the critical state (C3), but without this implying negative set speeds, since it is about not assisting above the maximum speed limit and not limiting the absolute speed of the bicycle (Vb).

[0056] In an alternative embodiment, a regenerative state could be provided in which, starting from a preselected vehicle speed, the first electric machine (eM1) will operate at negative speeds, i.e., in generator mode, recharging the batteries and preventing the vehicle from exceeding that speed.

[0057] (X) Detect a fourth critical state (C4) in which the cadence (Wc) decreases below a minimum cadence threshold (Wc(min)) which may mean that the cyclist is stopping pedaling.

[0058] (XI) Set the set speed of the first electric machine (Wem1(con)) to zero. In this case, the electric assistance is instantly suspended and the critical state (C4) is exited.

[0059] (XII) Control the rotation speed of the first electric machine (Wem1) so that it reaches the setpoint speed (Wem1(con)) determined in (ll-XI).

[0060] In the control procedure just described, the user does not select a preset assistance level as is the case with other e-bikes—e.g., Eco, Tour, Turbo, etc.—but only the programmed cadence value (Wc(prog)). The actual level of electric assistance is a consequence of the cyclist's actions, both in terms of gear shifting (GS) and pedaling history.

[0061] The described control procedure does not necessarily have to be sequential in the order presented, as the control software will be programmed using state machines or other programming techniques. If state machines are used, the external variables would be read, the internal variables calculated, any state changes determined, and action taken based on the system / subsystem's current state(s). In any case, the described sequential procedure encompasses different software implementations, since these steps would be executed in different sequences in each of them.

[0062] Figure 4 shows a transient consisting of an initial acceleration zone from zero speed, characterized by the acceleration at the cyclist's cadence (Wc). When the cyclist reaches the set cadence (Wc(con)), the first electric machine (eM1) starts moving, in this particular case, proportionally to the area under the error curve. When the cadence returns to the set cadence, the speed of the first electric machine (eM1) stabilizes. It can also be seen that when the cyclist's cadence (Wc) decreases, the rotational speed of the first electric machine (Wm1) also decreases proportionally to the area under the error curve—negative in this case.

[0063] Figure 5 shows how, after an initial acceleration phase due solely to cadence (Wc), the first electric motor (eM1) begins to rotate at speed (Wm) until the bicycle's speed, proportional to the wheel's rotational speed (Wr), reaches 25 km / h. In this case, the setpoint speed (Wm(con)) is adjusted to ensure that the speed does not exceed 25 km / h with electric assistance. A fifth phase is also shown where the speed exceeds 25 km / h, but with the motor off and therefore no electric assistance.

[0064] Finally, Figure 6 shows how, before reaching the vehicle's maximum speed, the first electric motor (eM1) reaches a speed close to its maximum operating speed (Wm(max)). In this case, the modification of the first electric motor's operating speed (Wm) is shown to prevent exceeding this limit.

[0065] A second preferred embodiment of the present invention consists of a control procedure for an electrically assisted pedal vehicle equipped with an e-CVT with parallel hybridization at the output:

[0066] This vehicle will necessarily have a human-machine interface (HMI) that allows the selection of both the programmed cadence (Wc(prog)) and a level of electric assistance. This selected assistance level will be based on a multiple (K) of the input muscle power (Pe). Therefore, if the cyclist pedals at a certain cadence (Wc) and exerts a certain torque (Ce), the human mechanical power (PC) is known. If a specific multiple is selected from among the possible values ​​using the control device—e.g., K = 1.00—the mechanical assistance power (Pas) will be equal to the human mechanical power (Pe), since Pas = K PC. This assistance power will be provided by both electric motors in a proportion described in the control procedure.

[0067] We are considering a vehicle that is also subject to legislation imposing a maximum speed limit below which electric assistance is maintained. In this case, a specific cadence (CS) or speed (SS) sensor would not be necessary since the speed of the second electric motor (Wem2) is directly related to the vehicle's speed (Vb), and the cadence (Wc) is mathematically defined by the speeds of both motors through the power-split system.

[0068] In this vehicle, the preferred control procedure will act on the first electrical machine (eM1) in the same way as in the previous case, except for the detection and handling of critical states (C3 and C4), which in this case would be done differently. This control procedure would preferably comprise the following steps:

[0069] (I) - (Vil) Same steps as the previous procedure.

[0070] (VIII) Measure the resistive torque in the first electrical machine (Cerní) — e.g., by measuring its phase intensity (Iem1) — .

[0071] (IX) Determine the mechanical power supplied by the first electric machine (Pem1) from (VIII) and its measured rotational speed (Wem1).

[0072] (X) Determine the mechanical muscle power introduced by the cyclist (Pc) from the knowledge of the resistive torque in the first electric machine (Cerní) — proportional to the resistive torque on the cyclist (Ce) — and the measured cadence (Wc).

[0073] (XI) Detect a third critical state (C3), consisting of the bicycle speed being close to the maximum allowed under assistance conditions (e.g. 25 km / h Europe or 32 km / h USA),

[0074] (XII) Modify the value of the electric assistance level (K) — multiple of human power — in the vicinity of the speed limit so that its value is zero when reaching that limit — e.g. linearly from 1 to 0 in the vicinity of the limit — .

[0075] (XIII) Determine the assistance power (Pas) as the product between the assistance level (K) and the muscle mechanical power (Pe).(XIV) Determine the power that the second electric machine will supply (Pem2) as the difference between the assistance power (Pas) and the mechanical power supplied by the first electric machine (Pem1).

[0076] (XV) Determine the set point of the second electric machine (Cem2(con)) according to the power (Pem2) determined in (XIV) and the speed of the second electric machine (Wem2).

[0077] (XVI) Detect a fourth critical state (C4) in which the cadence (Wc) decreases below a minimum cadence threshold (Wc(min)) which may mean that the cyclist has stopped pedaling.

[0078] (XVII) Set both the speed setpoint of the first electric machine (Wem1(con)) and the moment setpoint of the second electric machine (Cem2(con)) to zero to exit the critical state (C4). In this case, all electrical assistance is instantly suspended (Pas = 0).

[0079] (XVIII) Control the rotational speed of the first electric machine (Wem1) so that it reaches the setpoint speed (Wem1(con)) determined in (11-VII and XVII). (XIX) Control the torque of the second electric machine (Cem2) so that it exerts the setpoint torque (Cem2(con)) determined in (XV and XVII).

Claims

CLAIMS 1. Cadence control procedure for a hybrid power divider drive, applicable to electric bicycles, comprising at least: or a muscle power (MP) input; or a power-split (PS) gear with a first transmission member — hereafter referred to as slow input (LS1) — , a second transmission member — hereafter referred to as fast input (HS1) — , and a third transmission member — hereafter referred to as slow output (LS2) — ; wherein the slow input (LS1) is mechanically and exclusively connected to a muscle power (PM) input without receiving any other power input; or a first electrical machine (eM1) mechanically connected to said fast input (HS), and electrically to a controller, to a source of electrical power, or to a control device or human-machine interface (HMI); or means of measuring (CS) pedaling cadence (Wc); where said power output member (LS2) is mechanically connected to at least one wheel of the vehicle (RM); where said control device or human-machine interface (HMI) allows the user to choose a cadence that he / she would like to maintain — hereinafter referred to as programmed cadence (Wc(prog)) — ; and where said control procedure is characterized by the fact that it acts in such a way that the first electric machine (eM1) introduces more or less power into the power-split gear (PS), generating a greater or lesser resistive moment on the human power input (PM), so that the pedaling cadence (Wc) will be slowed down or accelerated, thus managing to maintain, within a wide range of operating conditions, a value close to the programmed cadence (Wc(prog)).

2. Cadence control procedure according to claim 1, applicable to vehicles with a single electric machine and a mechanical gear-changing system, comprising at least the following steps: (I) Determining the error (e) as the difference between the measured cadence of the cyclist (Wc) and the set cadence (Wc(con)); (II) Determine a set speed (Wem1(con)) for the first electric machine (eM1) according to a function of the instantaneous value of the error (e) and / or the historical value of said error (e): Wem1(con)) = F(e(r); T=0, r=t); (III) Measure the speed of the bicycle (Vb) using the speed sensor (SS); (IV) Detect a first critical state (C1) consisting of the setpoint speed (Wem1(con)) determined in (II) being higher than a value corresponding to the maximum speed of the first electric machine determined by its manufacturer (Weml(max)); (V) Reduce the setpoint speed of the first electric machine (Wem1(con)) and / or temporarily increase the setpoint rate (Wc(con)) to get out of the critical state (C1); (VI) Detect a second critical state (C2) in which the resistive moment (Cerní) on the first electric machine (eM1) causes the electric current (Iem1) to reach a critical value, or the power maintained for a certain time to be higher than a legal limit or induce critical temperatures in the system; (Vil) Modify the setpoint speed of the first electric machine (Wem1(con)) and / or temporarily the setpoint rate (Wc(con)) to avoid the critical state (C2). (VIII) Detect a third critical state (C3), consisting of the bicycle speed (Vb) being higher than the maximum allowed under electric assistance conditions; (IX) Modify the set speed of the first electric machine (Wembl(con)) to get out of the critical state (C3), but without this implying negative set speeds, since it is about not assisting above the maximum speed limit and not limiting the absolute speed of the bicycle (Vb); (X) Detect a fourth critical state (C4) in which the cadence (Wc) decreases below a minimum cadence threshold (Wc(min)) which may mean that the cyclist is stopping pedaling; (XI) Set the setpoint speed of the first electric machine (Wem1(con)) to zero. In this case, the electric assistance is instantly suspended and the critical state (C4) is exited; (XII) Control the rotational speed of the first electric machine (Wem1) so that it reaches the setpoint speed (Wem1(con)) determined in (II-XI).

3. Cadence control procedure according to claim 1, applicable to electric bicycles equipped with an e-CVT with parallel hybridization at the output, wherein said control device (HMI) further allows the user to select a level of electric assistance that corresponds to a multiple (K) of the cyclist's muscle power (Pe), comprising the following steps: (I) - (VII) Same steps as the procedure corresponding to claim 2; (VIII) Measure the resistive torque in the first electrical machine (Cerní); (IX) Determine the mechanical power supplied by the first electric machine (Pem1) from (VIII) and its measured rotational speed (Wem1); (X) Determine the muscular mechanical power introduced by the cyclist (Pe) from the knowledge of the resistive torque in the first electric machine (Cerní), proportional to the resistive torque on the cyclist (Ce), and the measured cadence (Wc); (XI) Detect a third critical state (C3), consisting of the bicycle speed being close to the maximum allowed under assistance conditions; (XII) Modify the value of the electric assistance level (K) in the vicinity of the speed limit so that its value is zero when reaching that limit; (XIII) Determine the assistance power (Pas) as the product between the assistance level (K) and the muscle mechanical power (Pe); (XIV) Determine the power that the second electric machine (Pem2) will supply as the difference between the assisting power (Pas) and the mechanical power supplied by the first electric machine (Pem1); (XV) Determine the set point of the second electric machine (Cem2(con)) according to the power (Pem2) determined in (XIV) and the speed of the second electric machine (Wem2); (XVI) Detect a fourth critical state (C4) in which the cadence (Wc) drops below a minimum cadence threshold (Wc(min)) that may indicate the cyclist has stopped pedaling; (XVII) Set both the setpoint speed of the first electric machine (Wem1(con)) and the setpoint moment of the second electric machine (Cem2(con)) to zero to exit the critical state (C4). In this case, all electric assistance is instantly suspended (Pas = 0); (XVIII) Control the rotational speed of the first electric machine (Wem1) to reach the setpoint speed (Wem1(con)) determined in (I l-VI I and XVII); (XIX) Control the moment of the second electric machine (Cem2) so that it exerts the set moment (Cem2(con)) determined in (XV and XVII).

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