This invention applies to the electronic control of battery powered vehicles, such as electric bicycles, scooters and golf club transporters (ride-on and walk-behind), which use permanent magnet or shunt d.c. motors.

Our controller and power module combination has the following main features:

Subject to the terms set out in 3.2, we can now supply samples of our composite controller/power module for evaluation. The photographs below show the vehicle we built as the test bed for our development programme, and the finalised controller we will supply (now much smaller than when the vehicle photograph was taken in the early part of the development).

3.1  INSTALLATION.

3.3  TO ORDER A SAMPLE.

An email to us at pflemming@bigpond.com will set the wheels in motion. Please tell us initially:

4.1.  INTRODUCTION.

At starting and at all operating speeds, the selected position of the potentiometer in the motoring zone provides linear control of torque from zero to the maximum available from the motor at its current speed. Maximum operating current and torque are set by the user's choice of Rs, the low value resistance (0.01 to 0.03 ohms) in series with the armature.

4.1.2  BRAKING, REGENERATION AND BATTERY CHARGING.

When braking by using our system, regeneration and return of charge to the battery result, simply by moving the potentiometer through neutral to the regeneration zone. The amount of braking and the rate of charging are user controlled from zero to the maxima available at the current speed.

In our system, braking and regeneration always occur together. This is because the motor is acting as a generator, and external torque is required to drive it. This external torque is supplied by inertia, when vehicle and contents are slowed, or by gravity, when travelling downhill and braking to control travelling speed. Additional mechanical braking should be retained for heavy braking in an emergency, and for coming to a dead stop. Our braking and regeneration are zero at zero speed.

4.1.3  BENEFITS.

The benefits of our approach are:

Travelling downhill, the rider simply rotates the handle grip into the braking/battery charging zone. The handle grip rotation chosen will vary with the steepness of the hill and the speed at which the rider wishes to travel. The rider may also decide to peddle downhill, so as to increase the rate of battery charging, thereby adding to the recharging occurring due to gravity (more precisely, to conversion of potential energy).

The attraction and simplicity of this system results from the control of torque in place of speed. At all times, the rider determines how little or how much effort he or she will apply to peddling, and rotating the handle grip will become as automatic as operating the foot throttle and brake peddle of a car with automatic transmission. Indeed, the analogy is a close one, with our new rider having even easier control by turning a single handle grip, rather than having two peddles to operate.

Existing and intending electric bicycle manufacturers who order sample control and power modules from us, will require to provide their own handle grip/control potentiometer mock-ups for the advanced stages of their evaluation programmes. The mock-ups can be readily done with off-the-shelf motorbike handle grips and throttle cables, connecting to slide-pots and spring returns. In production, designs based on handle grips turning rotary pots through plastic spur gears, as illustrated in Figure 2, will provide a lower cost approach.

We remind those interested that our intended course is to arrive at one or more licensing arrangements. We do not intend involving ourselves directly in manufacturing or supply. We could, however, consider continuing associations on a consultancy basis.

4.3. WALK-BEHIND GOLF BUGGIES.

4.3.1. BASIC BUGGY FUNCTION.

In this application, the handle grip slides on the handle tube with a travel of about 5 cms (2 inches), this motion being imparted to the slide type control potentiometer by a connecting rod. The enclosed compression spring will typically require about 0.5 Kg (1 lb.) to commence its compression and about 1.5 Kg (3 lbs.) for full compression, that is, for full travel of the potentiometer. The golfer will simply walk behind the buggy, pushing on the handle grip with a force within the range of the spring, and our control system will do the rest. The motor will power the buggy on uphill sections and apply braking and return battery charge on downhill sections, at all times adjusting automatically to varying gradients. Our system not only automatically adjusts to gradients, but also to the golfer's walking speed.

This is far superior to current buggies we have examined in Australia. All are speed controlled by varying the voltage to the motor armature. The problem is that, for any voltage selected, speed varies considerably with motor load and hence gradient. The result is the need either to vary the control setting frequently, or to speed up and slow down one's walking. This hit and miss "control of the golfer by the buggy" can be particularly irritating if one is walking alongside a companion, or manoeuvring around tees and greens. Often, this leads to the golfer actually pulling back on the buggy, thereby wasting battery energy. In contrast, the comfortable 1 to 3 lbs. applied forwards by our golfer throughout the round saves battery energy, adding to the main saving through regeneration.

A further problem with current buggies is lack of braking. These days, the call of "FOUR" can either mean a ball in flight, or a buggy running away, downhill. With our control system, the buggy is left with the handle grip in the regeneration zone. If released on a steep hill, our buggy will creep slowly down, without the likelihood of damaging itself or injuring someone.

For those golfers who, in addition to welcoming our system just described, may want to retain hands-off cruise control on long level fairways, we have also developed and tested a controller with two potentiometers. The control handle grip and first potentiometer are as shown in Figure 3, The handle grip has the added function of rotating, in the neutral zone only, the second (cruise control) potentiometer, which is operated by a sliding extension of the connecting rod. We have thus been able to maintain the simplicity of single handle grip control, with automatic changeover between the two modes of travelling.

4.3.2. REDUCTION DRIVES.

To gain the benefits of regenerative braking and energy recovery, chain drives or straight-through gearing, preferably helical, are essential on walk-behind golf buggies. At the reduction ratios involved, worm drives will either lock up, or run so inefficiently as to nullify regenerative energy return.

4.3.3. OVERRUNNING CLUTCHES.

For ease of steering around corners, a means of catering for the rotational speed difference between the two driving wheels must be provided. In this regard, we have seen buggies with a separate motor driving each wheel, and there are probably buggies around which include differentials. However, the great majority employ overrunning clutches and this provides a good low cost solution.

To incorporate regeneration, it is necessary for the wheels to drive the motor and this, of course, cannot happen with the above unidirectional overrunning clutches. To overcome this, we have designed a solenoid operated reversible overrunning clutch which interfaces with our control system. In the motoring zone, the motor drives the rear wheels, with the outer wheel overrunning during cornering. In the regeneration zone, the wheels drive the motor, with the inner wheel being overrun during cornering.

A further feature of our clutch is that when de-energised, it completely frees the wheels from the motor and reduction unit. This applies whenever the main switch on the buggy is turned off. The buggy is then free to be pushed or pulled with minimum effort.

As the design proceeded, it became clear that the unit would have applications well beyond our golf buggy. Accordingly, we have lodged a separate Provisional Patent Application and have added  a separate page to this web site, giving details of the design and it's applications. Whilst we have not yet completed prototyping and testing, we are confident regarding performance and cost viability.

4.3.4. EVALUATION BY INTERESTED PARTIES.

We propose that existing and intending golf buggy manufacturers evaluate our system in two stages.

1. Obtain a controller/power module sample from us and trial it in a buggy with its overriding clutches locked up, or the drive otherwise made solid. Whilst this will mean straight-line travelling in the main, it will allow adequate evaluation of the excellent "feel" of the control system, along with establishing the benefits of regenerative braking and the return of charge to the battery. It will be necessary to mock up a suitable handle assembly to perform as illustrated in Figure 3. We can supply a drawing of our prototype, if this will assist.
2. Prototype and fit reversing overriding clutches, based on clutch springs and basic drawings we can provide on agreed terms, but customised to best suit the manufacturer's present or intended configuration of motor, reduction drive and wheel axles. We expect to make springs and basic drawings available in the next two to three months.

We are confident that the results of such evaluations will bear our own vehicle tests, and our claims arising from them.

4.4.1. PRESENT PRODUCTS.

Our research indicates that:

1. Most manufacturers are not tapping the full potential for regenerative braking and for optimising efficiency by return of energy to the battery.
2. Most sales are of units with a single motor, reduction gears, a simple (not a limited) differential, and single braking via the motor shaft. These vehicles are subject to wheel-spin, with loss of power or braking, when on a slippery surface under one wheel, or by inside wheel lift during cornering. Four-wheel scooters can also lose traction by lifting a rear wheel when mounting kerbs At least two scooter manufacturers in Australasia are fitting a motor, reduction unit and braking on each driving wheel, in order to avoid the shortcomings of simple differentials.
3. Pulse Width Modulation (PWM) of voltage is now generally used for control of motor speed and therefore indirectly of motor torque. Our system is more rapid and responsive since we control motor torque directly.

4.4.2. OUR APPROACH.

We believe that adoption of our reversible overrunning clutch and control system in these product groups has the potential to:

4.4.2.1. REVERSIBLE OVERRUNNING CLUTCH.

We introduced this concept in Section 3 on golf buggies. In that application, the motion is forward only, except when the main switch is turned off, in which condition the buggy simply freewheels in either direction. The added requirement in this present application is the need to reverse. In this regard, our clutch design operates equally well in either direction. Thus, all that is required is to switch electrically to "reverse" and the three requirements, motoring, regenerating and cornering, perform equally as well as in the forward direction.

4.4.2.2. CONTROL SYSTEM.

We can deal briefly with this, since the basics are essentially the same as have been outlined in Sections 2 and 3. In summary:

4.4.2.3. EVALUATION BY INTERESTED PARTIES.

As proposed for golf buggies in Section 4.3.4, we recommend that this proceed in two stages:

1. Manufacturers of vehicles having differentials should commence by obtaining samples of our controller,  noting again that, at this stage, we are only catering for 12 volt systems. Where their maximum motor currents are 60 amps or less, they can use our controller and power module directly. Manufacturers with motor currents exceeding 60 amps will need to liase with us and we will fit additional mosfets on our heat sinks. The fitting of controller and power module, together with a suitable potentiometer arrangement (refer Figure 4), will be all that is required to evaluate the excellent "feel" and performance of our control system.
2. To evaluate our new clutch design, manufacturers will require to source two prototypes along the lines set out in Section 4.3.4. Somewhat heavier springs will be required than for golf buggies. We will be happy to consult on their design, if requested.