TECHNICAL FIELD

The present disclosure relates to a controller module for highly dynamic loads. Aspects relate to a controller for a power supply system for a vehicle suspension system, a system, a vehicle, a method of operating a controller for a power supply system for a vehicle suspension system, and a non-transitory computer readable medium.

BACKGROUND

Vehicles, in particular electric or hybrid vehicles, comprise active suspension systems, such as an electronic active roll control system, for maintaining vehicle stability. A suspension system for a vehicle may reduce the forces experienced by the vehicle and the users of the vehicle as a result of a condition of a road or other driving surface.

The actuators of a suspension system may have a high power requirement, so may require a different, higher value, power source to the other components of the vehicle. This is particularly pertinent for the actuators of electronic active roll control systems. The use of a separate power source can have a negative impact on the rest of the electrical and communication networks of the vehicle.

A suspension system may have short-term, high power requirements so the suspension system may generate and consume energy with a high transient content. This is particularly relevant for electronic active roll control systems, which can generate or consume several kilowatts of power with peaks lasting as little as a millisecond. These operational characteristics can create significant amounts of electrical noise which can destabilise existing vehicle power supply systems.

It is an aim of the present disclosure to address one or more of the disadvantages associated with the prior art.

SUMMARY OF THE INVENTION

Aspects and embodiments of the invention provide a control system, a system, a vehicle and a method as claimed in the appended claims

According to an aspect there is provided a controller for a power supply system for a vehicle suspension system. The power supply system comprises a power converter; a first circuit comprising an electrical energy supply; and a second circuit. The power converter is arranged to separate the first and second circuits and is electrically connected to the first and second circuits respectively. The controller is configured to control the power converter to maintain an average target voltage in the second circuit between lower and upper target voltage values by causing the power converter to transfer power from the first circuit to the second circuit if the voltage in the second circuit is below the lower target voltage value, and causing the power converter to transfer power from the second circuit to the first circuit if the voltage in the second circuit is above the upper target voltage value.

The power converter is configured to operate between the first circuit operating at a first voltage and the second circuit operating at a second voltage. The second voltage may be greater than the first voltage. The first voltage may be 12V and the second voltage may be 48V.

Moreover, the average target voltage may be 46V, the lower target voltage value may be 44V and the upper target voltage value may be 48V.

Advantageously, the transfer of power between the first and second circuits helps to maintain an average target voltage in the second circuit. If the voltage in the second circuit deviates from the average target voltage enough to be outside lower and upper target voltage values, the transfer of power between the first and second circuits can bring the voltage of the second circuit back within the upper and lower target voltage values.

Further advantageously, it is not necessary to incorporate any further components in the power supply system to maintain the average target voltage in the second circuit between the lower and upper target voltage values. The power supply system is able to regulate the voltage of the second circuit without requiring any further inputs.

Optionally, the second circuit comprises an electrical energy storage module. The controller is further configured to control the power converter to maintain the average target voltage in the second circuit between the lower and upper target voltage values by causing the power converter to draw power from the electrical energy storage module if the voltage in the second circuit is below the average target voltage and above the lower target voltage value, and causing the power converter to supply power to the electrical energy storage module if the voltage in the second circuit is above the average target voltage and below the upper target voltage value. Advantageously, the power supply system is able to further regulate the voltage of the second circuit to be closer to the average target voltage.

Further advantageously, the regulation of the voltage of the second circuit is achieved using the components of the second circuit. It is not necessary to transfer power to or from the first circuit so electrical noise generated by the transfer of power between the first and second circuits is reduced or eliminated. The power supply system is therefore less likely to destabilise as a result of electrical noise.

Further advantageously, the power supply system is able to smoothen the transient power demands of the second circuit to a stable long term average. The lower and upper target voltage values form a buffer region such that the second circuit is not disturbed by the first circuit when the voltage of the second circuit is within this buffer region. This improves the stability of the second circuit.

Further advantageously, the electrical energy storage module mitigates the impact of some of the electrical energy peaks and troughs arising in the second circuit. The electrical energy storage module receives or provides electrical energy to the second circuit when a voltage of the second circuit is within the buffer region. That is, when the voltage of the second circuit is within the buffer region, the electrical energy storage module acts to regulate the volage of the second circuit. This reduces the load acting on both a generator of the second circuit and the power converter between the first and second circuits.

Optionally, the second circuit further comprises a switch electrically connected between the electrical energy storage module and the power converter. The controller is further configured to control the switch to connect the electrical energy storage module into the second circuit to cause the electrical energy storage module to receive charge from the electrical energy supply.

Optionally, the controller is further configured to receive an indication to power down the second circuit; set the electrical energy storage module to a predetermined storage voltage; and open the switch to isolate the energy stored within the electrical energy storage module from the second circuit.

Optionally, the controller is further configured to receive an indication that a bus voltage on the second circuit has reached a control voltage limit. Optionally, the controller is further configured to control the power converter to maintain the average target voltage in the second circuit between the lower and upper target voltage values in response to receiving the indication that the bus voltage has reached the control voltage limit.

Optionally, the upper and lower target voltage values are determined based on an electrical characteristic of one or more of the power converter and the electrical energy storage module.

Optionally, the electrical energy storage module comprises a supercapacitor module.

Optionally, the controller is further configured to determine whether one or more of the power converter and the electrical energy storage module have entered a fault state.

Optionally, the controller is further configured to provide the average target value as a setpoint to the power converter.

Optionally, the power converter comprises a bidirectional DCDC power converter.

According to another aspect, there is provided a system comprising a power supply system for a vehicle suspension system and a controller.

According to a further aspect, there is provided a vehicle comprising a controller or a system.

According to another aspect, there is provided a method of operating a controller for a power supply system for a vehicle suspension system of a vehicle. The power supply system comprises a power converter, a first circuit comprising an electrical energy supply, and a second circuit. The power converter is configured to separate the first and second circuits and is electrically connected to the first and second circuits respectively. The method comprises controlling the power converter to maintain an average target voltage in the second circuit between lower and upper target voltage values, by causing the power converter to transfer power from the first circuit to the second circuit if the voltage in the second circuit is below the lower target voltage value; and causing the power converter to transfer power from the second circuit if the voltage in the second circuit is above the upper target voltage value.

According to a further aspect, there is provided computer software that, when executed, is configured to perform any method disclosed herein. Optionally the computer software is stored on a computer readable medium. Optionally the computer software is tangibly stored on a computer readable medium.

Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and/or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and/or features of any embodiment can be combined in any way and/or combination, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and/or incorporate any feature of any other claim although not originally claimed in that manner.

BRIEF DESCRIPTION OF THE DRAWINGS

One or more examples will now be described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 shows a controller of a diagnostic apparatus according to examples disclosed herein;

Figure 2a shows a control system for a vehicle connected to front and rear anti-roll bars according to examples disclosed herein;

Figure 2b shows a control system for a vehicle comprising plural sub-systems, and front and rear anti-roll bars according to examples disclosed herein;

Figure 3 shows a schematic topology of an anti-roll control system according to examples disclosed herein;

Figure 4 shows an example flow diagram of controller operation according to examples disclosed herein;

Figure 5 shows an example flow diagram of controller operation according to examples disclosed herein; and

Figure 6 shows a vehicle according to examples disclosed herein.

DETAILED DESCRIPTION

Active suspension systems, such as electronic active roll control utilizing mechatronic systems, may include a cascade of systems, such as: (a) a high level vehicle control layer, which may generate system demand signals (for example torque demands) to influence vehicle motion;

(b) a low level control layer, which may provide control signals to actuators (for example motor control) to deliver the demanded signal from the high level control; and

(c) a physical actuation layer, comprising motors and associated mechanical components to deliver the physical manifestation of the demanded signal.

The actuators of a suspension system may have a high power requirement, so may require a different, higher value, power source to the other components of the vehicle. This is particularly pertinent for the actuators of electronic active roll control systems. The use of a separate power source can have a negative impact on the rest of the electrical and communication networks of the vehicle.

A suspension system may have short-term, high power requirements so the suspension system may generate and consume energy with a high transient content. This is particularly relevant for electronic active roll control systems, which can generate or consume several kilowatts of power with peaks lasting as little as a millisecond. These operational characteristics can create significant amounts of electrical noise which can destabilise existing vehicle power supply systems.

Examples disclosed herein may be controlled to act as a power supply buffer and smooth the transient demand to achieve a stable long term average power.

With reference to Figure 1 , there is illustrated a control system 100 for a power supply system for a suspension system of a vehicle. The control system 100 comprises one or more controllers 110. The control system 100 as illustrated in Figure 1 comprises one controller 110, although it will be appreciated that this is merely illustrative. The controller 110 comprises processing means 120 and memory means 130. The processing means 120 may be one or more electronic processing device 120 which operably executes computer-readable instructions. The memory means 130 may be one or more memory device 130. The memory means 130 is electrically coupled to the processing means 120. The memory means 130 is configured to store instructions, and the processing means 120 is configured to access the memory means 130 and execute the instructions stored thereon.

The controller 110 comprises an input means 140 and an output means 150. The input means 140 may comprise an electrical input 140 of the controller 110. The output means 150 may comprise an electrical output 150 of the control system 100. The input 140 is configured to receive one or more input signals 165, for example from a sensor 160. The inputs may be either physical (for example from a hard wired sensor) and/or may be from a vehicle communication bus. There may be one or more sensors which provide information to the controller input 140. The output 150 is configured to provide one or more output signals 155.

A controller 100 may be for a power supply system for a vehicle suspension system. Such a power supply system may comprise a power converter, a first circuit comprising an electrical energy supply, and a second circuit. The power converter may be arranged to separate the first and second circuits and electrically connect to the first and second circuits respectively. The controller 100 may then be configured to control the power converter to maintain an average target voltage in the second circuit between lower and upper target voltage values. The controller 100 may do so by causing the power converter to transfer power from the first circuit to the second circuit if the voltage in the second circuit is below the lower target voltage value, and causing the power converter to transfer power from the second circuit to the first circuit if the voltage in the second circuit is above the upper target voltage value. In this way the controller may maintain the voltage in the second circuit within a predetermined voltage range. In such an example, the input 140 may therefore arranged to receive signals indicating the voltage in the second circuit as input 165. The output 150 may therefore arranged to provide a power transfer signal to the first circuit to cause power transfer from the first to the second circuit, and/or provide a power transfer signal to the second circuit to cause power transfer from the second to the first circuit, as output signals 155.

Figures 2a and 2b illustrate example control system 200 for a suspension system of a vehicle. A suspension system of a vehicle may comprise anti-roll bars 270, 280 which are controlled using an anti-roll control system. The anti-roll control system acts to control the anti-roll bars, to control a roll of a body of the vehicle and reduce the impact of disturbances from a road surface. The anti-roll control system may be electromechanical and/or hydraulic. Anti-roll bars 270, 280 may typically comprise stabiliser bars, typically metal, which join the vehicle suspension on either side of the vehicle axle, usually through drop links, and connect to a rotational actuator situated between the mounting points to the vehicle chassis. Each side of the anti-roll bar is able to rotate freely when a motor of the anti-roll control system is not energised. When the motor control is enabled (i.e. delivering torque), the anti-roll bar may act as a torsional spring. The anti-roll bars may be controlled to compensate for some vehicle movements such as body roll, for example from driving around a corner. Body roll can cause the wheels at the side of the vehicle outside the turn to reduce their contact with the road surface. Anti-roll bars may be controlled to counteract this effect and reduce the body roll effect, by transferring at least part of the additional load on the wheels at the side of the vehicle inside the turn to those wheels at the outside, for example by providing a torsional effect to pull the wheels towards the chassis and even out the imbalance in load on the wheels caused by cornering.

A typical suspension system may comprise passive front and rear anti-roll bars provided respectively between the front and rear pairs of wheels of a standard four-wheel vehicle. In a vehicle with an active roll control system, an anti-roll bar 270, 280 may comprise two anti-roll bar ends 273 and 274, 283 and 284, connected together by a central housing having an actuator 272, 282. The central housing may additionally have one or more of a gearbox, sensors, and dedicated actuator controllers. The actuator acts to provide an actively controlled torque rather than a fixed torsional stiffness provided by passive anti-roll bars. One or more sensors may monitor the movement of the vehicle, and provide the sensed parameters as input to the active roll control system to control the actuator and provide a suitable torque to the anti-roll bar. The two ends of the anti-roll bar (273, 274; 283, 284) may be identical, or may be non-identical.

Figure 2a shows an example control system 200 for a suspension system a vehicle, communicatively connected to front and rear anti-roll bars 270, 280. The control system 200 comprises a controller 240 which is connected by a communication channel 245 to anti-roll bar controllers 250, 260 configured to respectively control front and rear anti-roll actuators 272, 282. The controller 240 may be the controller 110 of Figure 1. The controller 240 may comprise one or more of the controllers 110 of Figure 1. In an example, the controller 240 may be a master controller for an electronic active roll control system in the vehicle. The controller 240 may host a vehicle level control strategy and actuation control for the electronic active roll control system in the vehicle.

The controller 240 may be configured to receive one or more sensor signal 203 from one or more sensors attached to the vehicle. The one or more sensor signals 203 may comprise, for example, a signal from a respective suspension height sensor of the vehicle suspension; a signal from a respective motor position sensor for the anti-roll bar actuators 272, 282; a signal from a respective hub acceleration sensor of the vehicle; and a signal from a respective torque sensor for the anti-roll bar actuators 272, 282. A suspension height sensor may be configured to determine a sensor signal indicative of one or more of a height of a left side and a height of a right side of the vehicle suspension. A motor position sensor may be configured to determine a sensor signal indicative of a position of a respective motor of the anti-roll bar actuators 272, 282. A hub acceleration sensor may be configured to determine a sensor signal indicative of an acceleration of one or more hub of a wheel of the vehicle. A torque sensor may be configured to provide a measure of an existing torque generated in the system, as a result of a target torque demand being requested by the controller.

The controller 240 may be configured to receive one or more communication signals via a communications bus 205. The communications bus 205 may be configured to deliver data to the controller 240 from other subsystems within the vehicle. For example, the communications bus 205 may be configured to communicate a signal indicating a status of one or more modules 210, 220, 230 that are in communicative connection with the controller 240 to the controller 240. In another example, the communications bus 205 may be configured to communicate a command from the controller 240 to the one or more modules 210, 220, 230 that are in communicative connection with the controller 240. The one or more modules 210, 220, 230, are discussed further in relation to Figure 2b below. Signals transmitted over connections 203 or 245 may alternatively or additionally be transmitted over communications bus 205.

The controller 240 may be configured to generate system demand signals to influence a vehicle’s motion via the anti-roll actuators 272, 282. An actuator provided between a front pair of wheels of a vehicle may be called a front actuator. A front active roll control (FARC) module may be electrically connected to the front actuator, and may comprise the controller 250 to control the front actuator 270. Similarly, an actuator provided between a rear pair of wheels of a vehicle may be called a rear actuator. A rear active roll control (RARC) module may be electrically connected to the rear actuator and may comprise a controller 260 to control the rear actuator 280.

The front and rear anti-roll actuators 272, 282 comprises an electric motor which is controllable by the respective anti-roll controller 250, 260. Each of the front and rear anti-roll actuators 272, 282 may be controlled by its own respective anti-roll controller in some examples, or multiple anti-roll actuators may be controlled by a common anti-roll controller in some examples. Each of the anti-roll actuators 272, 282 may be individually controlled in some cases to improve the management of the roll of the body of the vehicle. The front and rear anti-roll actuators 272, 282 may be controlled by a control signal which is generated by the controller 240 may generate and output, through the output channel 245, to the anti-roll bar controllers 250, 260. The control signal may carry instructions to be implemented by the actuator, for example by providing a torque to apply to the anti-roll bar. For example, as discussed above, when the vehicle is cornering, a control signal may be transmitted to the anti-roll bar controllers 250, 260, which may in turn transmit a control signal via interface 255, 265, so that the front and read anti-roll actuators 272, 282 may mitigate a body roll effect Similarly, anti-roll bar controllers 250, 260 may transmit measured values from the anti-roll actuators to the controller 240 through output channel 245.

Figure 2b shows an example control system 200 for a vehicle comprising one or more modules 210, 220, 230, a controller 240 and front and rear anti-roll bars 270, 280. As in Figure 2a, the control system 200 comprises a controller 240 which is connected by a communication channel 245 to controllers 250, 260 configured to respectively control front and rear anti-roll bar actuators 270; 280. Further, the controller 240 of the control system 200 is in a communicative connection to the one or more modules 210, 220, 230 via a communications bus 205. The one or more modules 210, 220, 230 may be configured to perform functions relating to power supply of the suspension system. Module 210 may be a power control module configured to control a power supply system for the suspension system. Module 220 may be a conversion module configured to convert electrical energy output from a vehicle power supply system. In an example, the conversion module 220 may comprise a DC-DC converter. Module 230 may be a capacitor or supercapacitor module configured to store electrical energy for the suspension system. Together, conversion module 220 and capacitor module 230 may be configured to supply electrical energy to the controllers 250, 260, such that the anti-roll bar actuators 272, 282 can be actuated. Figure 2b illustrates these modules 210, 220, 230 as individual modules. However, there may be examples whereby components within the modules 210, 220, and 230 are included in a single module. Similarly, communications links 205 and 245 may be the same in some examples.

Figure 3 shows a schematic topology of an anti-roll control system circuit 300. The anti-roll control system circuit 300 may be an electronic anti-roll control system. The system circuit 300 comprises a DCDC convertor 306 for power conversion, which for example may be 12V/48V DCDC converter 306, and may be a bidirectional DCDC converter. The power supply system 300 comprises a power converter 306, a first circuit 302 comprising an electrical energy supply 310, and a second circuit 304, as set out in relation to Figure 3. The power converter 306 is arranged to separate the first 302 and second circuits 304. The power converter 306 is electrically connected to the first 302 and second circuits 304 respectively.

A battery based electrical circuit 302 (for example a 12V battery) is connected to the DCDC converter 306 at a first side; this circuit 302 may be called a first circuit 302. The first circuit 302 in this example comprises a constant DC source 308; a battery / power supply (for example 12V battery) 310, and a 12V load (for example resistor) 312 all connected in parallel and connected to a first side (here, the 12V side) of the DCDC converter 306. At a first side of the first circuit 302 the connection between components 308, 310, 312 is made via a first bus 322 operating at a first voltage (for example a 12V bus). At a second opposite side of the first circuit 302 the connection between components 308, 310, 312 is made via a first ground bus 324 forming a return circuit through ground.

An electrical energy storage module 314 circuit (for example a supercapacitor based energy storage circuit 304, such as a 48V supercapacitor) is connected to the DCDC converter 306; this circuit 304 may be called a second circuit 304. The energy storage module 314 may be considered to be located at a junction point which splits the power distribution between the front 318 and rear 320 sub-systems of the electric active roll control system, and provides a permanent pass through between the DCDC converter 306 and the electric active roll control motor controllers on the second bus 326. The actuators 318, 320 may connect to the motor controllers of the front and rear axle actuators via a 3-phase AC high voltage link.

The second circuit 304 may provide power to the anti-roll control system actuators 250, 260. The second circuit 304 in this example comprises: an electrical energy storage module 314 (for example a supercapacitor stack) in series with an isolation switch 316; a front axle actuator controller 318 such as actuator 350, and a rear axle actuator controller 320 such as actuator 360, with the electrical energy storage module branch 314, 316, front axle actuator component 318, and rear axle actuator component 320 connected in parallel with each other and connected to a second side (here, the 48V side) of the DCDC converter 306. At a first side of the second circuit 304 the connection between components 316, 318, 320 is made via a second bus 326 operating at a second voltage (for example a 48V bus). At a fourth opposite side of the second circuit 304 the connection between components 314, 318, 320 is made via a second ground bus 328 forming a return circuit through ground. The “bus” may be understood to be a part of the circuit in some examples, and may be understood to be a particular physical bus component in some examples.

Using a supercapacitor in the electrical energy storage module 314 of the second circuit 304 may allow for energy peaks to be accommodated, and may reduce the load on the generator and battery / power supply 310 of the first circuit electrical system 302 and the DCDC converter 306. The controllers disclosed herein may be advantageous to use with a supercapacitor based energy storage module 314 which starts operating at a low voltage (that is, substantially lower than the average target voltage, such as a low voltage of <16V). This is because supercapacitor cells may discharge more quickly than a battery when the vehicle is in a sleep state. The operation of the system 300 may store the supercapacitor cells 314 at a lower voltage than when operating, to help prolong cell life.

The controller 100, 200 discussed previously may be configured to control the operation of the DCDC converter 306 and the system circuit 300. In some examples, control of the anti-roll control element may be implemented by a first control module (for example a chassis control module), and control of the electrical circuit 302 may be implemented by a second control module (for example a gateway module).

Figure 4 shows an example flow diagram 400 of controller operation. The controller (for example controller 100, 240) is for a power supply system (for example system 300) of a vehicle suspension system (for example system 200). The process starts 402 and the controller 100, 240 is configured to determine 404 if the voltage in the second circuit 304 is between lower and upper target voltage values. If the voltage in the second circuit 304 is between lower and upper target voltage values then the process returns for a later check 404 of the same. The lower and target voltage value may be 44V, and the upper target voltage value may be 48V, giving a midpoint target voltage of 46V.

If the voltage in the second circuit 304 is not between lower and upper target voltage values, then the process continues to then check 406 if the voltage in the second circuit 304 is below the lower target voltage value or is above the upper target voltage value.

If the voltage in the second circuit 304 is below the lower target voltage value, the controller 100, 240 is configured to cause 408 the power converter 306 to transfer power from the first circuit 302 to the second circuit 304. This may be considered to be operation in a “Boost” mode, in which power is transferred from the first circuit 302 (for example from the 12V side of the system 300) to the second circuit side (for example to the 48V side of the system 300) when the 48V side bus voltage is below the lower target voltage value (for example less than a lower target voltage value of 44V). Operating in this “Boost” mode would bring the bus voltage up to 46V.

If the voltage in the second circuit 304 is above the upper target voltage value, the controller 100, 240 is configured to cause 410 the power converter 306 to transfer power from the second circuit 304 to the first circuit 302. This may be considered to be operation in a “Buck” mode, in which power is transferred from the second circuit 304 (for example from the 48V side of the system 300) to the first circuit side (for example to the 12V side of the system 300) when the 48V side bus voltage is greater the upper target voltage value (for example greater than an upper target voltage value of 48V). Operating in this “Buck” mode would bring the bus voltage down to 46V.

In this way the controller 100, 240 may control the power converter 306 to maintain an average target voltage (for example 46V) in the second circuit 304 between lower (for example 44V) and upper target voltage (for example 48V) values. This “self-control” mode of the DCDC controller to operate about a setpoint may be performed after closure of the isolation switch 316 and charging the second bus 326 to a control voltage limit of the second circuit which may be lower than the lower target voltage value, for example 36V. At this second bus voltage, the controller 100, 240 may instruct the DCDC converter 306 to be in the “self-control” mode and maintain the set-point of 46V as described above. That is, the second circuit 304 comprises a switch 316 electrically connected between the electrical energy storage module 314 and the power converter 306, and the controller is configured to control the switch 316 to connect the electrical energy storage module 314 into the second circuit 304 to cause the electrical energy storage module 314 to receive charge from the electrical energy supply 310 in the first circuit 302. Thus, the controller may be configured to control the power converter 308 to transfer charge to the second circuit 304 and bring the second circuit 304 bus 326 voltage up to a terminal voltage of the electrical energy storage module 314 to control the switch 316 to connect the electrical energy storage module 314 into the second circuit 304.

In other words, there is disclosed a method 400 of operating a controller for a power supply system for a vehicle suspension system of a vehicle. The power supply system comprises: a power converter, a first circuit comprising an electrical energy supply, and a second circuit. The power converter is configured to separate the first and second circuits and is electrically connected to the first and second circuits respectively. The method 400 comprises controlling the power converter to maintain an average target voltage in the second circuit within lower and upper target voltage values, by: causing the power converter to transfer power from the first circuit to the second circuit if the voltage in the second circuit is below the lower target voltage value 408; and causing the power converter to transfer power from the second circuit if the voltage in the second circuit is above the upper target voltage value 410.

In some examples, the controller may be further configured to act to maintain the voltage in the second circuit at an average target voltage (for example 46V) within the lower and upper target voltage values (for example 44V and 48V). Thus, the controller may be configured to control the power converter 306 to maintain the average target voltage in the second circuit 304 within the lower and upper target voltage values by causing the power converter 306 to draw power from the electrical energy storage module 314 if the voltage in the second circuit 304 is below the average target voltage and above the lower target voltage value; and causing the power converter 306 to supply power to the electrical energy storage module 314 if the voltage in the second circuit 304 is above the average target voltage and below the upper target voltage value. Thus even if the second circuit 304 voltage is within the lower and upper target voltage values the controller may act to nudge the voltage towards the average, or midpoint, between the two voltage values.

By maintaining an average set point on the second bus 326 in the second circuit 304 in this way, transients may be substantially prevented from passing back through the DCDC converter 306 to the primary circuit 302, by rejecting short transients, The controller may achieve this by limiting the rate at which the DCDC converter changes its output (slew rate).

The controller may cause power to be cut from being supplied to the second bus 326 on the second circuit 304 within a short timescale (for example sub 1s, for example, within 30ms) of a network signal being received, to help protect against a control failure of the system 300.

Figure 5 shows an example flow diagram of controller operation 500. At step 502 the controller determines whether the DCDC converter 306 and the second circuit 304 (which may be called a supercapacitor module in examples having a supercapacitor stack 314 as, or comprised as part of, the electrical energy storage module 314) have initialized successfully or have entered a fault state. That is, the controller may be configured to determine whether one or more of the power converter 306 and the electrical energy storage module 314 have entered a fault state.

If there is a fault state the system would operate in a fault mode 516. Provided there is no fault state, at stop 504 the controller instructs the DCDC converter 306 to pre-charge the second bus from around 0V to a target voltage equivalent to the second circuit 304 terminal voltage (for example 48V).

At step 506 the controller instructs the second circuit 304 to close the isolation switch 316.

At step 508, after closure of the isolation switch 316 and charging the second bus 326 to a control voltage limit (for example 36V), the controller instructs the DCDC converter 306 to be in the “self-control” mode and maintain the second voltage bus 326 set-point (for example of 46V). The controller is programmed to maintain the set-point. However, as described above, the DCDC converter 306 is controlled to react within, for example, a +/- 2V band, to boost the voltage when the second bus 326 voltage falls to below the lower target voltage value, and to buck the voltage when the second bus 326 voltage when it rises above the upper target voltage value. The upper and lower target voltage values may be determined based on one or more electrical characteristics of the power converter 306. The upper and lower target voltage values may be determined based on one or more electrical characteristics of the electrical energy storage module 314. The upper and lower target voltage values (i.e. the voltage range) may be determined, for example, by the sizing of the circuit components. Therefore, electrical characteristics on which the upper and lower target voltage values depend may include, for example, the capacity of the energy storage module 314, the power of the DCDC converter 306. Also, the nature of load, and power demand from the load 312 which the converter 306 and energy storage module 314 are providing power to may determine, in part, the upper and lower target voltage values.

The controller may be configured to receive an indication that a bus voltage on the second circuit 304 has reached a control voltage limit (for example 36V). The controller may be configured to control the power converter 306 to maintain the average target voltage in the second circuit 304 between the lower and upper target voltage values in response to receiving the indication that the second bus 326 voltage has reached the control voltage limit (for example 36V).

At step 510, when requested to power-down, the controller sets the electrical energy storage module 314 to its storage voltage before instructing it to isolate, i.e. by opening its isolation switch 316. In other words, the controller may be configured to receive an indication to power down the second circuit 304, set the electrical energy storage module 314 to a predetermined storage voltage, and open the switch 316 to isolate the energy stored within the electrical energy storage module 314 from the second circuit 304. Setting the electrical energy storage module 314 to a predetermined storage voltage may be achieved by the controller providing the target voltage setpoint (for example 46V) to the converter 306.

The controller may provide all setpoints to the converter 306. Setpoints may be provided for both the first circuit 302 and the second circuit 304. During a “Boost” phase, the setpoint may be provided by the controller to the second circuit 304 to set the second bus 326 voltage. During the “Buck” phase, the setpoint may be provided to both the first circuit 302 to set the first bus 322 voltage and the second circuit 304 to set the second bus 326 voltage.

At step 512 the controller instructs the DCDC converter 306 to discharge the second bus 326 and provides a setpoint. At step 514 the controller sets the system 300 and the system components to enter a sleep mode.

Where there are discussions of electrical charge it will be appreciated these discussions could be framed in terms of electrical energy for example through the relation energy = charge x voltage).

While the discussion above relates to control of power for electrical active roll control systems, it may also be applied in other systems in which there is a highly dynamic load. These systems may include other actuator-based applications in different industries, such as the robotics or mechatronics systems industries. These systems may also include high voltage applications in the power industry, such as controlling generator (synchronous machine) performance, transmission line voltage control, and transmission line frequency control.

The blocks illustrated in Figures 4 and 5 may represent steps in a method 400, 500 and/or sections of code in a computer program configured to control the control system as described above to perform the method steps. The illustration of a particular order to the blocks does not necessarily imply that there is a required or preferred order for the blocks and the order and arrangement of the block may be varied. Furthermore, it may be possible for some steps to be omitted or added in other examples. Therefore, this disclosure also includes computer software that, when executed, is configured to perform any method disclosed herein, such as that illustrated in Figure 4 or Figure 5. Optionally the computer software is stored on a computer readable medium, and may be tangibly stored.

Figure 6 shows a vehicle 600 comprising a control system 100 as described above, or a system 100 as described above. The vehicle 600 in the present embodiment is an automobile, such as a wheeled vehicle, but it will be understood that the control system and active suspension system may be used in other types of vehicle.

As used here, ‘connected’ means ‘electrically interconnected’ either directly or indirectly. Electrical interconnection does not have to be galvanic. Where the control system is concerned, connected means operably coupled to the extent that messages are transmitted and received via the appropriate communication means.

It will be appreciated that various changes and modifications can be made to the present disclosed examples without departing from the scope of the present application as defined by the appended claims. Whilst endeavouring in the foregoing specification to draw attention to those features believed to be of particular importance it should be understood that the Applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to and/or shown in the drawings whether or not particular emphasis has been placed thereon.