BMW has taken to the IAA Mobility show in Munich, Germany, to unveil two new electric motorbikes with interesting specs for their categories. Both have the same performance figures, making for a high-speed electric bicycle and a low-speed electric motorbike.
The two models were technically unveiled by different divisions of BMW.
BMW unveiled the i Vision AMBY, which is a high-speed electric bicycle.
The company’s motorcycle division, BMW Motorrad, unveiled the Vision AMBY. That little “i” makes a big difference.
The i Vision AMBY may technically fall in the electric bicycle category, but it shares very little with its e-bike brethren. The frame uses similar suspension components to other high-end bicycles and what appears to be a Gates carbon belt drive, but the electronics appear to be entirely custom.
A higher-power motor and gigantic 2,000 Wh battery enable it to reach much higher speeds in its highest setting. That big battery also has BMW making lofty range claims of up to 300 km (186 miles) in its lowest power mode.
Using an accompanying smartphone app, riders can choose between the European legal 25 km/h (15.5 mph) speed, a second speed-pedelec mode that reaches 45 km/h (28 mph), and a new high-speed-pedelec mode that ups the ante to 60 km/h (37 mph). BMW even floated the idea of having those speeds be modifiable in real time based on geo-fencing, meaning you could be slowed down automatically when you hit the city center, then unleashed to your top speed once turning onto a larger road.
Don’t get too excited though – you’ll need to register the bike and get a special license plate to use it on public roads in anything other than the slowest mode.
This also isn’t an electric motorcycle in disguise. Those pedals are for more than show; they are required to power the motor. Without a hand throttle, riders will have to continue pedaling constantly to achieve and maintain the bike’s high speeds. The range rating also drops significantly to just 75 km (47 miles) when traveling at 60 km/h (37 mph).
The highest speed mode certainly doesn’t fit into any current legal designation for electric bicycles though.
BMW clarified further, saying:
“In the absence of any existing legal framework for a vehicle of this kind with a modular speed concept, the “AMBY” Vision Vehicles set out to prompt the introduction of such legislation and, by consequence, developments of this nature.”
The bike also features other interesting design elements, such as LED light bars integrated into the handlebars and seat post, as well as an angular frame with a highly tucked seating position.
On the other hand, the BMW Motorrad Vision AMBY electric motorcycle looks to be a much more leisurely ride.
Instead of a pair of pedals, the Vision AMBY swaps in more realistic motorcycle-style foot pegs.
Interestingly, the Vision AMBY e-motorcycle also hits the same top speed of 60 km/h (37 mph), which is rather slow compared to other entries in the light electric motorcycle class.
Ignition cranking during startup and load dumps during shutdown are common sources of voltage transients on an automotive supply line. These undervoltage (UV) and overvoltage (OV) transients can have significant magnitudes and will damage circuits that are not designed to operate during these extremes.
Specialized UV and OV protection devices have been developed to disconnect sensitive electronics from power supply transients. For example, protection devices can monitor the input supply using a window comparator and then validate that it is within range. Similarly, the supply voltage can be monitored by a resistive divider network connected to the UV and OV monitor pins. The window comparator output can then drive the gates of two N-channel MOSFETs that make or break the connection between the supply and the load. The window comparator can be designed with hysteresis on its monitor pins to improve noise immunity. Hysteresis can prevent false MOSFET on/off switching due to ripple or other high frequency oscillations on the supply line. For example, 25 mV of hysteresis is equivalent to 5% of the monitor pin thresholds and is common for UV and OV protection devices.
For their own protection or to reduce ignition loading, some automotive accessory circuits must be disconnected from the supply line during startup or shutdown. Due to the large transients involved, these circuits may require more hysteresis than the protection device can provide by itself. For such applications, the increased hysteresis requirement can be satisfied by matching the protection device with a supply monitor that has adjustable hysteresis. This article walks through how to design a wide voltage range automotive circuit protector.
Figure 1. Power path control with wide voltage monitor hysteresis
Automotive UV/OV and Overcurrent Monitor with Circuit Protection
The architecture shown in Figure 1 protects electronics that are sensitive to undervoltage, overvoltage, and overcurrent transients present on an automotive supply. Figure 1 is an example of a wide voltage range automotive circuit protector. In this circuit, an LTC4368 from Analog Devices serves as the specialized UV and OV protection device and is responsible for connecting the load to the supply. The role of the window comparator is managed by an LTC2966.
The LTC2966 monitors reverse voltage, undervoltage, and overvoltage conditions. Monitoring thresholds and hysteresis levels are configured by the resistor networks on the INH and INL pins and the voltages on the RS1 and RS2 pins. OUTA is the UV window comparator output and OUTB is the OV window comparator output. The polarity of these outputs can be selected to be inverting or noninverting with respect to the inputs via the PSA and PSB pins. In Figure 1, they are configured to be noninverting. The OUTA and OUTB outputs from the LTC2966 are pulled up to the REF pin of the LTC2966 and are fed directly to the UV and OV pins of the LTC4368.
The LTC4368 provides reverse current and overcurrent protection. The size of the current sense resistor, R11, determines the reverse current and overcurrent levels. The LTC4368 decides if the