Method for determining optimized operating point control parameters for controlling an inductive transformer for driving a rotor of an externally excited electric machine

Abstract

The invention discloses a method (100) for determining optimized operating point control parameters for controlling an inductive transformer (1) having a step-down converter (12) and a bridge circuit (13) for driving a rotor (40) of an externally excited electric machine, the method comprising: measuring transmission powers (110) of the inductive transformer (1); measuring temperatures (110) of a transformer unit (30) of the inductive transformer (1); measuring cooling temperatures (110) of at least one power semiconductor element of the step-down converter (12) and / or of at least one power semiconductor element of the bridge circuit (13); measuring primary link voltages (110) of the inductive transformer (1); determining an operating characteristic map (120) of the inductive transformer by means of the transmission power, the temperatures, the cooling temperatures and the primary link voltages; determining a minimum operating point control parameter and a maximum operating point control parameter (130) by means of the operating characteristic map according to an operating point for providing a required transmission power of the inductive transformer (1); determining a total power loss (140) of the inductive transformer (1) by means of the operating characteristic map according to the operating point; and determining, by means of the minimum operating point control parameter and the maximum operating point control parameter, the optimized operating point control parameter (150) for the operating point at which the total power loss is minimized.

Description

[0001] Description

[0002] Method for determining optimized operating point control parameters for controlling an inductive transformer for driving a rotor of a separately excited electric machine

[0003] The present invention relates to a method for determining optimized operating point control parameters for controlling an inductive transformer for driving a rotor of a separately excited electric machine.

[0004] In the prior art, a bridge circuit for adjusting the transmission power of an inductive transformer is known. The transmission power can be adjusted by means of a frequency used to control the bridge circuit.

[0005] Furthermore, operating strategies for minimizing losses in inductive transformers are known, which are based on the frequency for controlling the bridge circuit.

[0006] The object of the present invention is therefore to provide a technology that is more advanced than the prior art. In particular, it aims to improve the minimization of power loss in relation to transmission power.

[0007] This problem is solved by articles with the features according to the independent claims. Advantageous embodiments are the subject of the dependent claims.

[0008] A method for determining optimized operating point control parameters for controlling an inductive transformer with a buck converter and bridge circuit for driving a rotor of a separately excited electrical machine is disclosed. The method comprises acquiring power ratings within a power rating range of the inductive transformer, acquiring temperatures within a temperature range of a transformer within the inductive transformer, acquiring cooling temperatures within a cooling temperature range of at least one power semiconductor element of the buck converter and / or at least one power semiconductor element of the bridge circuit, and acquiring primary DC link voltages within a primary DC link voltage range of the inductive transformer.Furthermore, the method involves determining an operating characteristic of the inductive transformer using the transmission power, the temperatures, the cooling temperatures and the primary DC link voltages.

[0009] The operating point control parameter can, for example, be designed to set the output power of the inductive transformer.

[0010] The power transmission, the transformer temperature, the cooling temperature, and the primary DC link voltage can also be considered or described as operating parameters of the inductive transformer, the rotor, and the voltage source supplying the inductive transformer. Furthermore, these operating parameters can be considered as parameters that cannot be influenced by this process.

[0011] The transmission power range can, for example, encompass a range from the minimum possible transmission power of the inductive transformer to the maximum possible transmission power of the inductive transformer. The minimum possible transmission power can, for instance, be greater than the power required for the inductive transformer to operate. Furthermore, the maximum possible transmission power can, for example, be less than the power that would destroy the inductive transformer. Therefore, the minimum and maximum possible transmission power can be determined by the specific inductive transformer used.

[0012] The temperature range can, for example, encompass a range from a minimum possible temperature of the transformer to a maximum possible temperature of the transformer. The minimum possible temperature can, for example, be higher than the inductive transformer's own temperature that would lead to its destruction. Furthermore, the maximum possible temperature can, for example, be lower than the inductive transformer's own temperature that would lead to its destruction. In this respect, the minimum and maximum possible temperatures can be determined by the transformer used. The cooling temperature range can, for example, encompass a range from the minimum possible cooling temperature of the at least one power semiconductor to the maximum possible cooling temperature of the at least one power semiconductor.The minimum possible cooling temperature and the maximum possible cooling temperature can depend on, for example, the temperature resistance of the power semiconductors used.

[0013] The primary DC link voltage range can, for example, encompass a range from a minimum possible primary DC link voltage of the inductive transformer to a maximum possible primary DC link voltage of the inductive transformer. The minimum possible primary DC link voltage can, for instance, be greater than the minimum voltage required for the operation of the inductive transformer. Furthermore, the maximum possible primary DC link voltage can, for example, be lower than a voltage that would destroy the inductive transformer, particularly one of its primary windings. Therefore, the minimum and maximum possible primary DC link voltages can be determined by the specific inductive transformer used.

[0014] The respective areas can also be understood, for example, as the working area, working areas or operating area of ​​the respective electronic component.

[0015] The recorded values ​​can preferably be discretized, in particular within a permissible operating range of the inductive transformer, the transformer and / or at least one of the power semiconductor elements.

[0016] The operating characteristic curve can be determined, for example, by simulating the operating parameters. Furthermore, the operating characteristic curve can be determined by measuring or measuring a series of the operating parameters. In particular, the operating characteristic curve can be determined by measuring or measuring a series of the operating parameters when the inductive transformer drives the rotor.

[0017] The operating characteristic curve can, for example, be designed as a multidimensional curve. Determining the operating characteristic curve can also include analytical modeling of the losses of the individual components of the inductive transformer as a function of the operating parameters.

[0018] Furthermore, the method discloses a process for determining a minimum operating point control parameter and a maximum operating point control parameter using the operating characteristic map corresponding to an operating point in order to provide a required transmission power of the inductive transformer. The method further comprises determining the total power loss of the inductive transformer using the operating characteristic map corresponding to the operating point and determining the optimized operating point control parameter for the operating point at which the total power loss is minimized, using the minimum operating point control parameter and the maximum operating point control parameter.

[0019] The operating point can also be referred to as the operating point or operating state. The operating point can, for example, correlate with the transmission power of the inductive transformer. Furthermore, the operating point can be located within the respective operating range of the inductive transformer.

[0020] The required transmission power can, for example, depend on the electrical power required by the rotor. The electrical power required by the rotor can, in turn, depend on the operation of the separately excited electric machine.

[0021] The total power loss can include, for example, the power loss of the buck converter, the power loss of the bridge circuit, the power loss of the transformer, and / or the power loss of an AC bridge in the inductive transformer. The individual power losses can depend on the operating characteristics. The total power loss can be determined, for example, using a summation function of all power losses.

[0022] Minimizing total power loss can, for example, involve minimizing individual power losses. This could mean minimizing all individual power losses. Alternatively, it might be possible to minimize only the power loss of the buck converter, the power loss of the bridge circuit, the power loss of the transformer, and / or the power loss of the AC bridge. For instance, a summation function could be used to optimize total power loss.

[0023] In other words, the optimized operating point control parameter can depend on the power dissipation of a secondary bridge circuit of the inductive transformer, particularly a full bridge, the switching frequency of the bridge circuit, and / or a voltage, particularly a DC voltage, of the secondary bridge circuit. Furthermore, the optimized operating point control parameter can depend on conduction losses of the secondary bridge circuit due to the DC voltage, which in turn depends on the voltage of the primary side of the inductive transformer. Finally, the optimized operating point control parameter can depend on the power dissipation of diodes in the secondary bridge circuit, particularly due to the DC voltage, since the DC voltage influences the conduction time of the diodes and the peak current value of the secondary bridge circuit at low DC currents.Furthermore, the optimized operating point control parameter can depend on the transformer's power loss due to the switching frequency, although a minimum frequency is required to control the bridge circuit for transforming through the transformer. Additionally, the optimized operating point control parameter can depend on a maximum frequency for controlling the bridge circuit, which is limited by the switching speed of the power semiconductors. The maximum current of the inductive transformer can be limited by a maximum permissible current of the power semiconductors or the transformer, with this maximum current being used, for example, to determine a minimum DC voltage. Furthermore, the maximum DC voltage can be limited by a maximum permissible current pulse load of the power semiconductors on a secondary side of the inductive transformer.

[0024] This method can be used, for example, to determine the optimized operating point control parameter for providing the required output power to drive the rotor, thereby minimizing the overall power loss of the inductive transformer. The method allows for the control of two variable operating parameters of the inductive transformer: the primary voltage is set by the buck converter, and the output current fundamental frequency is set by the bridge circuit.

[0025] The buck converter can be used to preferably set a primary voltage of the inductive transformer, based on an input voltage of the inductive transformer. The input voltage can exceed a maximum voltage, particularly on the secondary side, and thus lead to the destruction of the electrical components on the secondary side. Therefore, the buck converter can be used to reduce the primary voltage so that the secondary voltage remains below the maximum voltage of the secondary side.

[0026] Furthermore, by using the minimum and maximum operating point control parameters, the power loss of the optimized operating point control parameter can be reduced due to the varying power losses of the inductive transformer. In this way, an optimized operating point control parameter can be preferably determined for different inductive transformers to control an optimal operating point.

[0027] Furthermore, the method can determine the optimized operating point control parameter for two or more operating points of the range.

[0028] For example, the respective procedural requirements can be implemented for the two or more operating points. The procedure can, for instance, first implement the requirements for the first of the two or more operating points and then for the second of the two operating points.

[0029] The number of operating points can depend, for example, on the operating range of the inductive transformer. Furthermore, the number of operating points can also depend on the operating range of the separately excited electric machine. In this context, the number of operating points can, for example, be determined by an operating point corresponding to a specific power output for driving the machine. Additionally, the minimization of power losses can be achieved through mathematical optimization, in particular Pareto front optimization.

[0030] Furthermore, constrained optimization methods such as nonlinear programming can also be used to minimize power loss.

[0031] For example, optimization parameters can be provided to the process, which were determined using mathematical optimization.

[0032] Furthermore, the operating point control parameter can include at least one control parameter for controlling the buck converter and / or one control parameter for controlling the bridge circuit.

[0033] The control parameter for the buck converter can, for example, be a voltage. The control parameter for the bridge circuit can, for example, be a frequency.

[0034] For example, a switching frequency for controlling the bridge circuit can result in particular in the power loss of the bridge circuit.

[0035] Furthermore, the procedure can also include providing the optimized operating point control parameters for controlling the inductive transformer.

[0036] The optimized operating point control parameter can be provided to a control unit for controlling the inductive transformer. The control unit can be designed and configured to set the operating point on the inductive transformer corresponding to the operating point control parameter.

[0037] Furthermore, the procedure can also include determining a lookup table with the optimized operating point control parameter and an associated operating point of the inductive transformer.

[0038] The lookup table can, in particular, contain optimized operating point control parameters for the two or more operating points. Furthermore, the lookup table can include operating point control parameters for all operating points. The method can also include providing the lookup table.

[0039] The lookup table can be provided to a control unit for controlling the inductive transformer. The control unit can be designed and configured to set the operating points on the inductive transformer that correspond to the operating point control parameters of the lookup table.

[0040] Furthermore, the procedure can also include controlling the inductive transformer using the lookup table.

[0041] Furthermore, a computing unit is disclosed which is designed and equipped to execute the disclosed procedure.

[0042] The computing unit can, for example, be designed as a separate computing unit, computer unit, or computer system.

[0043] The computing unit can preferably be configured and set up to determine the lookup table. Furthermore, the computing unit can preferably be configured and set up to provide the lookup table.

[0044] Furthermore, a vehicle is disclosed with a separately excited electric machine, an electric transformer and a disclosed computing unit, wherein the computing unit controls the electric transformer to drive a rotor of the electric machine.

[0045] The vehicle could be, for example, a car, a commercial vehicle, an aircraft, and / or a ship. The electric motor could, for example, be designed to propel the vehicle.

[0046] Preferably, the vehicle's computing unit can control the rotor using a provided lookup table. In other words, the lookup table can be predefined, created, and provided to the vehicle. The present invention is described in detail below with reference to the figures. These show:

[0047] Fig. 1 shows a flowchart of a method for determining optimized operating point control parameters for controlling an inductive transformer with buck converter and bridge circuit for driving a rotor of a separately excited electrical machine;

[0048] Fig. 2 shows an inductive transformer known from the prior art for driving a rotor of a separately excited electric machine; and

[0049] Fig. 3 shows an inductive transformer with buck converter and bridge circuit for driving a rotor of a separately excited electrical machine according to a control of the disclosed method.

[0050] The present invention is described below with reference to preferred embodiments and the figures. However, this description of embodiments should not be considered exhaustive.

[0051] Fig. 1 shows a method 100 for determining optimized operating point control parameters for controlling an inductive transformer 1 with buck converter 12 and bridge circuit 13 for driving a rotor 40 of a separately excited electrical machine.

[0052] Method 100 further comprises the acquisition of operating parameters 110. This includes the acquisition of transmission powers within a transmission power range of the inductive transformer 1, the acquisition of temperatures 110 within a temperature range of a transformer 30 of the inductive transformer 1, the acquisition of cooling temperatures 110 within a cooling temperature range of at least one power semiconductor element of the buck converter 12 and / or at least one power semiconductor element of the bridge circuit 13, and the acquisition of primary DC link voltages 110 within a primary DC link voltage range of the inductive transformer 1. Furthermore, Method 100 comprises the determination of an operating characteristic map 120 of the inductive transformer using the transmission power, the temperatures, the cooling temperatures, and the primary DC link voltages.

[0053] Furthermore, the method 100 includes determining a minimum operating point control parameter and a maximum operating point control parameter 130 using the operating characteristic map corresponding to an operating point to provide a required transmission power of the inductive transformer 1.

[0054] Furthermore, the procedure 100 includes determining a total power loss 140 of the inductive transformer 1 using the operating characteristic map according to the operating point.

[0055] Likewise, the procedure 100 includes determining the optimized operating point control parameter 150 for the operating point at which the total power loss is minimized, using the minimum operating point control parameter and the maximum operating point control parameter.

[0056] For example, the operating point control parameter can include a control parameter for controlling the buck converter 12 and a control parameter for controlling the bridge circuit 13.

[0057] Furthermore, the procedure 100 can include providing the optimized operating point control parameters for controlling the inductive transformer 1.

[0058] Furthermore, the method 100 can include determining a lookup table with the optimized operating point control parameter and an associated operating point of the inductive transformer 1.

[0059] Furthermore, procedure 100 can include providing the lookup table.

[0060] Furthermore, the method 100 can include controlling the inductive transformer 1 using the lookup table.

[0061] Fig. 2 shows an inductive transformer 1 known from the prior art for driving a rotor 40 of a separately excited electric machine. The inductive transformer 1 comprises a primary side 10 and a secondary side 20. The primary side 10 has a primary DC link capacitor 11 and a bridge circuit 13. The secondary side 20 has a secondary bridge circuit 21 and a secondary DC link capacitor 22.

[0062] The bridge circuit 13 processes an input voltage, which is provided, for example, by a vehicle battery.

[0063] Furthermore, the electrical circuit arrangement includes a transformer 30, which is designed for the inductive transmission of the voltage processed by the bridge circuit 13 from the primary side 10 to the secondary side 20.

[0064] The transmitted voltage is further processed by the secondary bridge circuit 21 and the voltage processed by the secondary bridge circuit 21 is smoothed by the secondary intermediate circuit capacitor 22.

[0065] The smoothed voltage is supplied by the secondary intermediate circuit capacitor 22 to the rotor 40 of an electric machine of the vehicle.

[0066] The voltage or output power provided by the inductive transformer 1 can be controlled by the bridge circuit 13. For example, the bridge circuit 13 can control the output power by means of a control level. The control level can, for example, include a control signal designed to control or switch the bridge circuit 13.

[0067] Fig. 3 shows an inductive transformer 1 with buck converter 12 and bridge circuit 13 for driving a rotor 40 of a separately excited electrical machine, which can be controlled according to the disclosed method 100.

[0068] The inductive transformer 1 comprises a primary side 10 and a secondary side 20. The primary side 10 includes a primary DC link capacitor 11, a buck converter 12, and a bridge circuit 13. The secondary side 20 includes a secondary bridge circuit 21 and a secondary DC link capacitor 22. The bridge circuit 13 processes an input voltage, which is supplied, for example, by a vehicle battery.

[0069] Furthermore, the electrical circuit arrangement includes a transformer 30, which is designed for the inductive transmission of the voltage processed by the bridge circuit 13 from the primary side 10 to the secondary side 20.

[0070] The transmitted voltage is further processed by the secondary bridge circuit 21 and the voltage processed by the secondary bridge circuit 21 is smoothed by the secondary intermediate circuit capacitor 22.

[0071] The smoothed voltage is provided by the secondary intermediate circuit capacitor 22 to the rotor 40 of the vehicle's electric machine.

[0072] The voltage or output power provided by the inductive transformer 1 can be controlled by the buck converter 12 and the bridge circuit 13. For example, the buck converter 12 can control the output power by means of a voltage, and the bridge circuit 13 can control it by means of a frequency.

[0073] The buck converter 12 and the bridge circuit 13 are controlled by means of optimized operating point control parameters provided by the method 100. The output power of the inductive transformer 1 can be controlled by the method.

[0074] Reference symbol list

[0075] 100 procedures

[0076] 110 Recording operating parameters

[0077] 120 Determining an operating characteristic map 130 Determining a minimum operating point control parameter and a maximum operating point control parameter

[0078] 140 Determining total power loss

[0079] 150 Determining the optimized operating point control parameter

[0080] 1 inductive transformer 10 primary side

[0081] 11 Primary intermediate circuit capacitor

[0082] 12 buck converters

[0083] 13 Bridge circuit

[0084] 20 Secondary side 21 Secondary bridge circuit

[0085] 22 Secondary intermediate circuit capacitor

[0086] 30 Transformer

[0087] 40 Rotor

Claims

Claims 1. Method (100) for determining optimized operating point control parameters for controlling an inductive transformer (1 ) with buck converter (12) and bridge circuit (13) for driving a rotor (40) of a separately excited electrical machine, comprising: Measurement of transmission power (110) of a transmission power range of the inductive transformer (1 ); Detection of temperatures (110) of a temperature range of a transformer (30) of the inductive transformer (1 ); Detection of cooling temperatures (110) of a cooling temperature range of at least one power semiconductor element of the buck converter (12) and / or at least one power semiconductor element of the bridge circuit (13); Detection of primary DC link voltages (110) of a primary DC link voltage range of the inductive transformer (1 ); Determining an operating characteristic map (120) of the inductive transformer using the transmission power, the temperatures, the cooling temperatures and the primary intermediate circuit voltages; Determining a minimum operating point control parameter and a maximum operating point control parameter (130) using the operating characteristic map corresponding to an operating point to provide a required transmission power of the inductive transformer (1 ); Determining the total power loss (140) of the inductive transformer (1) using the operating characteristic curve according to the operating point; and Determining the optimized operating point control parameter (150) for the operating point at which the total power loss is minimized, using the minimum operating point control parameter and the maximum operating point control parameter.

2. Method according to claim 1, characterized in that the method further determines the optimized operating point control parameter for two or more operating points of the range.

3. Method according to claim 1 or 2, characterized in that The minimization of power loss is carried out by means of mathematical optimization, in particular Pareto front optimization.

4. Method according to one of claims 1 to 3, characterized in that the operating point control parameter comprises at least one control parameter for controlling the buck converter (12) and / or one control parameter for controlling the bridge circuit (13).

5. Method according to one of claims 1 to 4, characterized in that the method further comprises providing the optimized operating point control parameters for controlling the inductive transformer (1 ).

6. Method according to one of claims 1 to 5, characterized in that the method further comprises determining a lookup table with the optimized operating point control parameter and an associated operating point of the inductive transformer (1 ).

7. Method according to claim 6, characterized in that the method further comprises providing the lookup table.

8. Method according to claim 7, characterized in that the method further comprises controlling the inductive transformer (1) by means of the lookup table.

9. Computing unit designed and configured to perform the method according to any one of claims 1 to 8.

10. Vehicle comprising a separately excited electric machine, an electric transformer (1 ) and a computing unit according to claim 9, wherein the computing unit controls the electric transformer (1 ) to drive a rotor (40) of the electric machine.

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