Electromagnetic suspension system

F/OEngineeringandTechnology
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Mahindra Igniters
Independent Suspension
• Greater ride comfort,
• Safer
• Stable on/off road
• Better traction
Beam Axle Suspension
• Simple in Construction
• Inexpensive
• Greater loading capacity
• Low self weight
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Electromagnetic
Suspension System
Prepared by
Bilal Hasan Syed
6th Semester
B.Tech Mechanical Engg.
Jamia Millia Islamia
Mahindra Igniters Solution

Classification of suspension
systems
Suspension
system
Active
Hydraulic
Pneumatic
Electro-
magnetic
Passive
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Hydraulic Suspension System
Examples of vehicles employing this technology
• BMW has recently developed an antiroll control (BMW-ARC)
system by placing a hydraulic rotary actuator in the center of
the antiroll bar at the rear of the vehicle as shown on figure in
next slide.
• Mercedes has developed an Active Body Control
System, which uses high-pressure hydraulics to pre-stress the
spring, hence generating antiroll forces without coupling the
left and right wheels (as in the case of an antiroll bar).
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Hydraulic Suspension System
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Fig no. 1 ARC system of BMW using a hydraulic rotary actuator

Hydraulic/Pneumatic
Suspension System
Advantages are
• Very high force density
• Ease of control
• Ease of Design
• Commercial availability of various parts
• Reliability
• Commercial Maturity
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Hydraulic/Pneumatic
Suspension System
Disadvantages are
• considered inefficient due to the required continuously
pressurized system;
• relatively high system time constant (pressure loss and
flexible hoses);
• environmental pollution due to hose leaks and ruptures,
where hydraulic fluids are toxic;
• mass and intractable space requirements of the total
system, including supply system, even though it mainly
contributes to the sprung mass.
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Electro-magnetic Suspension
System
Basic Idea
Magnetic repulsion can be used to absorb shocks. And since
response to input signals is very fast in electro-magnetic
induction motors, its use can give beneficial results.
Linear motion can be achieved by an electric rotary motor with a
ball screw or other transducers to transform rotary motion to
linear translation. However, the mechanism required to make this
conversion introduces significant complications to the system.
These complications include backlash and increased mass of the
moving part due to connecting transducers or gears that convert
rotary motion to linear motion (enabling active suspension).
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Electro-magnetic Suspension
System
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Overcomes the disadvantages of hydro/pneumatic suspension
as follows-
• No need for continuous power,
• Ease of control,
• Absence of fluids
• Relatively high Bandwidth (tens of hertz)

Bose Suspension System
It consists of
• Linear electro magnetic motors attached on each wheel,
• Power amplifiers at each wheel,
• A set of control algorithms.
Working
• This linear electromagnetic motor responds quickly enough to
counter the effects of bumps and potholes while maintaining
a comfortable ride.
• Electrical power is delivered to the motor by a power amplifier
in response to signals from the control algorithms.
• The bidirectional power amplifier allows power to flow into
the linear electromagnetic motor and allows power to be
returned from the motor.
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- An application of EM suspension

This suspension system requires less than a third of the power
of a typical vehicle’s air-conditioning system, i.e., hundreds of
watts. Compared with hydraulic actuators, the main advantages
of electromagnetic actuators are as follows:
• Increased efficiency,
• Improved dynamic behavior,
• Stability improvement,
• Accurate force control,
• Dual operation of the actuator.
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Fig no. 2- Bose Suspension System

Driving through curves
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Driving through long Bumps
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The disadvantages are as follows:
• Increased volume of the suspension, since the force density of
the active part of hydraulics is higher than for electromagnetic
actuation, i.e., system mass and volume could be less;
• Relatively high current for a 12- to 14-V system;
• Conventional designs that need excitation to provide a
continuous force;
• Higher system costs.
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Proposed Design
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Basic Idea
To combine the use of both Active and Passive suspension. The
general Macpherson system can be used and the passive shock
absorber can be replaced by electromagnetic dampers.
Basic Components
• Electromagnetic Damper
• Passive Coil Spring
• Power supplier
• Control Unit

Proposed Design
General Modification
For an electromagnetic coil to be used in a Macpherson type of
suspension system, its shape has to be modified.
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F
Fig no. 3 Linear Electromagnetic coil of Bose System

Proposed Design
General Modification
It has to be made into a cylindrical shape or moreover a tubular
shape so that it can be adjusted in Macpherson system.
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F
Fig no. 4 coil shape of the proposed design

Proposed Design
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Coil spring
Passive
damper
Permanent
Magnets
Bump stop
Encoder
Shaft
3 phase
Coil
Coil
springs
Permanent
magnets
(A) (B) (C)
Fig no. 5 Suspension struts. (a) Passive. (b) Active interior-magnet TPMA, (c)
Active exterior-magnet TPMA.

Proposed Design
Working
When the vehicle moves on the road the irregularities are sensed by
the control unit sensors. Power is supplied by the to EM dampers.
Signals are sent to Electromagnetic dampers which extend/withdraw
according to need. Wheels would then trace the path of irregularity.
Entire process would take fractions of second to initiate. The extra
shocks would be absorbed by the passive coil spring.
Power Regeneration
The bidirectional power supplies allows power to flow into the tubular
electromagnetic motor and allows power to be returned from the
motor. For example, when the suspension encounters a pothole,
power is used to extend the motor and isolate the vehicle’s occupants
from the disturbance. On the far side of the pothole, the motor
operates as a generator and returns the power back through the
supplies.
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Proposed Design
Safety
In general, the contact with the road surface is increased. When a
car turns through corner or curves, the effect of body roll is
almost eliminated. This would decrease the chance to topple over
the sides making it safer for the passenger. Also the smoother
movement of the vehicle, would prevent damage of the
mechanical parts. Thus, making safer for the parts of vehicle.
Ride-Comfort
The fast response of this system, is able to cancel out the
vibration up to a very large extent making it very comfortable.
Fail Safe
Even if the power supply fails, the passive spring would still
absorb the shocks and the regenerative power would help run the
EM damper.
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Proposed Design
Limitation
• A lot of research still has to be done to bring this design into
usable technology
• In general, the entire system installation cost is expected to be
quiet high.
Cost Cut-outs
• Comparing to Bose system only a shock absorber has to be
changed, hence cost compared to Bose sys should be less.
• Operating cost is less, since comparatively a low power is
required to operate.
• Comparing to active hydraulic system, its cost would be very
less. (no use of compressors, lesser power consumption)
• On observing level of comfort, safety and loading;
compensation could be made.
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Conclusion
• Active suspension offers many benefits over conventional and
semi-active suspension systems
• Electromagnetic suspension is a high bandwidth and efficient
solution for improving handling and comfort
• Proposed design of tubular permanent magnet coil in
dampers offers a high force density and fail-safe solution.
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Electromagnetic suspension system

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