Control system for a power transmission system
A three-loop control system with varying response times and regulator types addresses power management challenges in electric vehicles, ensuring stable voltage and reduced computational complexity, thereby enhancing system stability and component longevity.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- AMPERE SAS
- Filing Date
- 2025-10-16
- Publication Date
- 2026-04-23
AI Technical Summary
Existing power management systems for electric vehicles face challenges such as converter losses, complexity, and the need for robust real-time control to manage multiple energy sources, ensuring stable voltage and power delivery while compensating for fluctuations.
A control system with three loops - a fast loop, intermediate loop, and slow loop - each regulated by different response times and types of regulators, including higher-order sliding mode and proportional regulators, to manage current, DC bus voltage, and energy storage device voltage, respectively, with cross-control ensuring stability and reduced computational complexity.
The system provides precise and stable power supply to the DC bus, reducing disturbances and extending component lifespan by maintaining a stable voltage, while simplifying computational demands and compensating for non-minimum phase behavior of power converters.
Smart Images
Figure EP2025079949_23042026_PF_FP_ABST
Abstract
Description
[0001] DESCRIPTION
[0002] TITLE: Control system for a power transmission system
[0003] Technical field of the invention
[0004] The present invention relates to a control system for regulating the transmission of electrical energy from an energy generator and an energy storage device to a DC bus connected to a load.
[0005] State of the art
[0006] The rise of electric vehicles has led to significant advances in managing the power supplied to these vehicles, particularly for systems that combine various energy sources such as fuel cells and storage devices. These systems must provide a stable voltage adapted to the vehicle while delivering the power required for proper vehicle operation.
[0007] The fuel cell, although efficient at providing continuous energy, must be complemented by energy storage elements, such as batteries or supercapacitors, in order to meet instantaneous power requirements and compensate for fluctuations in power demand.
[0008] In general, each power source is coupled to a power converter, allowing for precise control of the power flow to the vehicle. However, this type of power management system presents challenges, notably the losses associated with the converters.
[0009] It is therefore important to implement a control strategy that ensures not only the required power is supplied to the vehicle, but also the stability of the supplied electrical signal. The control strategy must manage the dynamics of the various components, such as the state of charge of the storage devices, while maintaining a stable voltage to guarantee vehicle performance.
[0010] Another challenge for energy management systems combining multiple energy sources lies in their complexity, which requires sophisticated control systems and significant computing power. Finally, the robustness of the entire system must be continuously verified in real time to ensure its stability, particularly in the face of rapid variations in power demand and voltage fluctuations. Object of the invention
[0011] The present invention aims to provide a solution that addresses all or part of the aforementioned problems.
[0012] This goal can be achieved through the implementation of a control system to regulate the transmission of electrical energy from a power generator and an energy storage device to a DC bus connected to a load; the control system includes:
[0013] - a first control loop, called the fast loop, configured to regulate a current supplied by the energy generator and the storage device, via at least one first regulator having an initial response time,
[0014] - a second control loop, called the intermediate loop, configured to regulate a DC bus voltage, via a second regulator having a second response time,
[0015] - a third control loop, called the slow loop, configured to regulate a voltage of the energy storage device, via a third regulator having a third response time, the first response time being less than the second response time, and the second response time being less than the third response time.
[0016] Advantageously, the control system provides the required power to the load and supplies the DC bus with the required voltage precisely while reducing disturbances and ensuring increased stability.
[0017] The control system may also have one or more of the following characteristics, taken alone or in combination.
[0018] According to one characteristic, at least one first regulator is a higher-order sliding mode control regulator, and the second and third regulators are each proportional regulators.
[0019] Advantageously, the use of at least one higher-order sliding mode control or super-twisting controller reduces computational complexity in the control system, notably by reducing the number of differential control equations to be solved in the control system.
[0020] Advantageously, using at least one control regulator allows for compensation of the non-minimum phase behavior of power converters. In other words, this means that the control system can correct or adjust for undesirable effects caused by the way power converters respond to changes.
[0021] According to one characteristic, the fast loop uses two higher-order sliding mode control regulators, and the intermediate loop and slow loop each use a proportional regulator.
[0022] By "the fast loop uses two higher-order sliding mode control regulators, and the intermediate loop and the slow loop each use a proportional regulator", it is understood that the fast loop includes two higher-order sliding mode control regulators, and the intermediate loop and the slow loop each include a proportional regulator.
[0023] According to one characteristic, the DC bus voltage is used to calculate an input to the intermediate loop and the voltage of the storage device is used to calculate an input to the slow loop.
[0024] According to a characteristic, an output from the intermediate loop and an output from the slow loop serve as a setpoint for the fast loop.
[0025] Advantageously, this allows for cross-control, ensuring robustness of the control system and providing a stable voltage to the DC bus.
[0026] According to one characteristic, a fast loop output is a control signal intended to control an electrical converter disposed between the load on one side, and the energy generator and energy storage device on the other.
[0027] Advantageously, modifying the duty cycle of the control signal allows the power supplied to the load to be controlled.
[0028] According to one characteristic, the first response time is at least ten times shorter than the second response time, and the second response time is at least eight times shorter than the third response time.
[0029] Advantageously, it is possible to ensure that the first loop evolves at a sufficiently rapid dynamic compared to the second loop, and that the second loop evolves at a sufficiently rapid dynamic compared to the third loop, thus ensuring the stability of the control system.
[0030] Depending on one characteristic, the energy generator is chosen from a fuel cell and a renewable energy source, for example a solar panel, and the energy storage device is chosen from a supercapacitor and a battery. Summary description of the drawings
[0031] Other aspects, objectives, advantages, and features of the invention will become clearer upon reading the following detailed description of preferred embodiments thereof, given by way of non-limiting example, and made with reference to the accompanying drawings in which:
[0032] [Fig. 1] is a schematic representation of an energy transmission system comprising an energy generator and an energy storage device.
[0033] [Fig.2] is a block diagram that represents a control system for the transmission system in Figure 1.
[0034] Detailed description
[0035] In the figures and throughout the description, the same references represent identical or similar elements. Furthermore, the various elements are not drawn to scale in order to prioritize clarity in the figures.
[0036] Figure 1 shows an example of a power transmission system comprising a power generator and an energy storage device.
[0037] The transmission system includes an energy storage device 2 connected to a first DC power converter 1 and an energy generator 1 connected to a second DC power converter 2. The first DC power converter 1 and the second DC power converter 2 are connected to a DC bus 3 which is connected to a load 4.
[0038] The energy generator 1 can, for example, be a fuel cell or a renewable energy source, for example a solar panel.
[0039] The energy storage device 2 can be a supercapacitor or a battery.
[0040] Load 4 can be an electric machine from an electric vehicle connected to a DC bus 3.
[0041] The first DC1 electrical converter can be a buckboost converter for example and the second DC2 converter can be a boost type converter.
[0042] The first DC1 power converter includes a switch or transistor driven by a control signal having a first duty cycle of 1-d1, and the second DC2 converter includes a switch or transistor driven by a control signal having a second duty cycle of 1-d2. By controlling the first duty cycle 1-d1 and the second duty cycle 1-d2, it is possible to influence the electrical power delivered to load 4. It is important to deliver the power demanded by load 4 while maintaining a stable DC bus voltage 3.
[0043] Figure 2 presents a control system 10 for regulating the transmission of electrical energy in the energy transmission system described above.
[0044] Control system 10 includes:
[0045] - a first control loop, called the fast loop, configured to regulate an isc, ifc current supplied by the energy generator 1 and the storage device 2, via at least one first regulator ST 1, ST2 having a first response time,
[0046] - a second control loop, called the intermediate loop, configured to regulate a DC bus voltage Vbus, via a second regulator P1 having a second response time,
[0047] - a third control loop, called the slow loop, configured to regulate a voltage of the energy storage device Vsc, via a third regulator P2 having a third response time.
[0048] The first response time is shorter than the second response time, and the second response time is shorter than the third response time. For example, the first response time may be at least ten times shorter than the second response time, and the second response time may be at least eight times shorter than the third response time.
[0049] Advantageously, it is thus possible to ensure that the first loop evolves at a sufficiently rapid dynamic compared to the second loop and that the second loop evolves at a sufficiently rapid dynamic compared to the third loop, which ensures the stability of the control system 10.
[0050] For example, the first response time may be equal to 0.022 seconds, the second response time may be equal to 0.29 seconds, and the third response time may be equal to 2.5 seconds.
[0051] The third response time can be calculated so as to limit a current pulse to less than 4 Amperes / second.
[0052] Advantageously, a current pulse of less than 4 Amperes / second can extend the lifespan of components.
[0053] Current and voltage regulation in control system 10 can be done in real time. Figure 2 shows, for each block, an input signal and an output signal.
[0054] In the example in Figure 2, the fast loop uses two higher-order sliding mode control regulators, ST1 and ST2. "Higher-order sliding mode control regulators" refers to a super-twisting regulator in Anglo-Saxon terminology.
[0055] The ST1 regulator has as input a difference ei-sc between a measured current of the storage device isc and a current setpoint of the storage device i*sc, and as output a signal having a duty cycle of 1 -d 1 and intended to control the DC1 converter.
[0056] The ST2 regulator has as input a difference ei-fc between a measured current from the energy generator ifc and a setpoint of energy generator current i*fc, and as output a signal having a duty cycle of 1-d2 and intended to control the DC2 converter.
[0057] The intermediate loop uses a first proportional regulator P1. Regulator P1 takes as input a difference ev-bus between a measured DC bus voltage Vbus and a DC bus voltage setpoint V*bus, and as output the storage device current setpoint i*sc. Regulator P1 therefore converts the difference ev-bus into the current setpoint i*sc.
[0058] The slow loop uses a second proportional regulator, P2. Regulator P2 takes as input the difference ev-sc between a measured voltage of the storage device Vsc and a voltage setpoint of the storage device V*sc, and as output the current setpoint i*fc of the energy generator. Regulator P2 therefore converts the difference ev-sc into the current setpoint i*fc.
[0059] The current from the energy generator (ifc) and the current from the energy storage device (isc) are supplied to the DC bus 3.
[0060] The fast loop has a shorter response time than the intermediate loop. In other words, the intermediate loop does not perceive the regulation performed by the fast loop because the fast loop operates at a significantly faster rate, for example, ten times faster, than the intermediate loop.
[0061] Similarly, the intermediate loop has a shorter response time than the slow loop. In other words, the slow loop does not perceive the regulation performed by the intermediate loop because the intermediate loop operates at a significantly faster rate, for example, ten times faster, than the slow loop. The blocks of control system 10 operate independently, and it is therefore advantageous to modify one control block without modifying the entire control system 10.
[0062] The control system 10 can be stored in an on-board computer intended to control the transfer of electrical energy from the energy generator 1 and the energy storage device 2 to the vehicle.
[0063] Advantageously, control system 10 allows a singular perturbation strategy to be applied to said control system 10 so as to simplify the analysis of control system 10 by decomposing control system 10 into different control loops evolving at different time scales.
[0064] Advantageously, the singular perturbation strategy treats the fast loop as a stable control loop, and simplifies the slow loop by replacing a complex model of the fast loop with an approximation to a first-order system.
[0065] Advantageously, the control system 10 ensures robust and precise control to provide a constant Vbus voltage to the DC bus and prevent oscillations in said Vbus voltage. This allows for a stable power supply to the electric vehicle, thereby extending the service life of the various components of the power transmission system.
Claims
DEMANDS 1. Control system (10) for regulating the transmission of electrical energy from an energy generator (1) and an energy storage device (2) to a DC bus (3) connected to a load (4), the control system (10) comprising: - a first control loop, called the fast loop, configured to regulate a current (isc, ifc) supplied by the energy generator (1) and the storage device (2), via at least one first regulator (ST1, ST2) having a first response time, - a second control loop, called the intermediate loop, configured to regulate a DC bus voltage (Vbus), via a second regulator (P1) having a second response time, - a third control loop, called the slow loop, configured to regulate a voltage of the energy storage device (Vsc), via a third regulator (P2) having a third response time, the first response time being less than the second response time, and the second response time being less than the third response time.
2. Control system (10) according to claim 1, wherein at least one first regulator (ST1, ST2) is a higher-order sliding mode control regulator, and the second regulator (P1) and the third regulator (P2) are each a proportional regulator.
3. Control system (10) according to any one of claims 1 or 2, wherein the fast loop uses two higher-order sliding mode control regulators (ST1, ST2), and the intermediate loop and the slow loop each use a proportional regulator (P1, P2).
4. Control system according to any one of the preceding claims wherein the DC bus voltage (Vbus) is used to calculate an input of the intermediate loop (ev-bus) and the storage device voltage (Vsc) is used to calculate an input (ev-sc) of the slow loop.
5. Control system (10) according to any one of the preceding claims wherein an output of the intermediate loop (i*sc) and an output of the slow loop (i*fc) serve as setpoints for the fast loop.
6. Control system (10) according to any one of the preceding claims in which an output of the fast loop (1-d1, 1-d2) is a control signal intended to control an electrical converter disposed between the load (4) on the one hand, and the power generator (1) and the energy storage device (2) on the other hand.
7. Control system (10) according to any one of the preceding claims wherein the first response time is less than the second response time by at least ten times, and the second response time is less than the third response time by at least eight times.
8. Control system (10) according to any one of the preceding claims wherein the power generator (1) is selected from a fuel cell and a renewable energy source, for example a solar panel, and the energy storage device (2) is selected from a supercapacitor and a battery.