Method and device for controlling generator-side terminal voltage of converter, and controller of converter

1. A method for controlling a generator-side terminal voltage of a converter, the method comprising:

determining an upper limit of the generator-side terminal voltage based on a present voltage value of a direct-current (DC) bus of the converter, wherein the generator-side terminal voltage is a voltage of an output terminal of a generator, and the output terminal of the generator is connected to the converter;

determining an optimal value of the generator-side terminal voltage from a preset optimal search interval, wherein the optimal value minimizes a present value of a generator-side current when compared with other values in the preset optimal search interval, wherein the generator-side current is a current of the output terminal of the generator; and

setting a target value of the generator-side terminal voltage based on the upper limit of the generator-side terminal voltage and the optimal value of the generator-side terminal voltage, wherein the target value is used to obtain a control reference value of the generator-side terminal voltage,

wherein determining the optimal value of the generator-side terminal voltage comprises:

determining whether a present value of the generator-side terminal voltage falls into the preset optimal search interval; and

responsive to the present value of the generator-side terminal voltage falling into the preset optimal search interval, searching in the preset optimal search interval for the optimal value of the generator-side terminal voltage that minimizes the present value of the generator-side current; and

wherein searching in the preset optimal search interval for the optimal value of the generator-side terminal voltage that minimizes the present value of the generator-side current comprises:

step (a): setting the target value of the generator-side terminal voltage to an initial value, and obtaining a value I0 of the generator-side current and a given torque value T0 of the generator after the generator-side terminal voltage is stable;

step (b): updating the target value of the generator-side terminal voltage as a sum of the initial value and ΔU, and when the generator-side terminal voltage is stable and the given torque value is T0, determining whether a value I1 of the generator-side current is less than I0, wherein when I1 is greater than I0, step (c) is performed, or, when I1 is less than I0, step (e) is performed;

step (c): updating the target value of the generator-side terminal voltage as a difference between the initial value and ΔU, and when the generator-side terminal voltage is stable and the given torque value is T0, determining whether a value I2 of the generator-side current is less than I0, wherein when I2 is greater than I0, the initial value is determined as the optimal value of the generator-side terminal voltage that minimizes the present value of the generator-side current, or, when I2 is less than I0, step (d) is performed;

step (d): reducing the target value of the generator-side terminal voltage by ΔU, and when the generator-side terminal voltage is stable and the given torque value is T0, determining whether the present value of the generator-side current is smaller than a previous value of the generator-side current, wherein when the present value of the generator-side current is not smaller than the previous value of the generator-side current, the target value of the generator-side terminal voltage is determined as the optimal value of the generator-side terminal voltage, or, when the present value of the generator-side current is smaller than the previous value of the generator-side current, step (d) is repeated; and

step (e): increasing the target value of the generator-side terminal voltage by ΔU, and when the generator-side terminal voltage is stable and the given torque value is T0, determining whether the present value of the generator-side current is smaller than the previous value of the generator-side current, wherein when the present value of the generator-side current is not smaller than the previous value of the generator-side current, the target value of the generator-side terminal voltage is determined as the optimal value of the generator-side terminal voltage or, when the present value of the generator-side current is smaller than the previous value of the generator-side current, step (e) is repeated,

wherein ΔU is greater than 0.

2. The method according to claim 1 , wherein setting the target value of the generator-side terminal voltage comprises:

when the optimal value of the generator-side terminal voltage exceeds the upper limit of the generator-side terminal voltage, setting the target value of the generator-side terminal voltage to be equal to the upper limit of the generator-side terminal voltage; or

when the optimal value of the generator-side terminal voltage does not exceed the upper limit of the generator-side terminal voltage, setting the target value of the generator-side terminal voltage to be equal to the optimal value of the generator-side terminal voltage.

3. The method according to claim 1 , wherein determining the upper limit of the generator-side terminal voltage further comprises:

determining the upper limit of the generator-side terminal voltage further based on at least one of a preset maximum availability of a voltage of the DC bus, a voltage loss corresponding to a dead time of an Insulate-Gate Bipolar Transistor (IGBT) module in a generator-side rectifier unit of the converter, or an on-state voltage drop of the IGBT module in the generator-side rectifier unit of the converter.

4. A controller of a converter, comprising:

a processor; and

a memory having computer programs stored thereon, wherein the computer programs, when executed by the processor, implement a method for controlling a generator-side terminal voltage of the converter, the method comprising:

determining an upper limit of the generator-side terminal voltage based on a present voltage value of a direct-current (DC) bus of the converter, wherein the generator-side terminal voltage is a voltage of an output terminal of a generator, and the output terminal of the generator is connected to the converter;

determining an optimal value of the generator-side terminal voltage from a preset optimal search interval, wherein the optimal value minimizes a present value of a generator-side current when compared with other values in the preset optimal search interval, wherein the generator-side current is a current of the output terminal of the generator; and

setting a target value of the generator-side terminal voltage based on the upper limit of the generator-side terminal voltage and the optimal value of the generator-side terminal voltage, wherein the target value is used to obtain a control reference value of the generator-side terminal voltage,

wherein determining the optimal value of the generator-side terminal voltage comprises:

determining whether a present value of the generator-side terminal voltage falls into the preset optimal search interval; and

responsive to the present value of the generator-side terminal voltage falling into the preset optimal search interval, searching in the preset optimal search interval for the optimal value of the generator-side terminal voltage that minimizes the present value of the generator-side current; and

wherein searching in the preset optimal search interval for the optimal value of the generator-side terminal voltage that minimizes the present value of the generator-side current comprises:

step (a): setting the target value of the generator-side terminal voltage to an initial value, and obtaining a value I0 of the generator-side current and a given torque value T0 of the generator after the generator-side terminal voltage is stable;

step (b): updating the target value of the generator-side terminal voltage as a sum of the initial value and ΔU, and when the generator-side terminal voltage is stable and the given torque value is T0, determining whether a value I1 of the generator-side current is less than I0, wherein when I1 is greater than I0, step (c) is performed, or, when I1 is less than I0, step (e) is performed;

step (c): updating the target value of the generator-side terminal voltage as a difference between the initial value and ΔU, and when the generator-side terminal voltage is stable and the given torque value is T0, determining whether a value I2 of the generator-side current is less than I0, wherein when I2 is greater than I0, the initial value is determined as the optimal value of the generator-side terminal voltage that minimizes the present value of the generator-side current, or, when I2 is less than I0, step (d) is performed;

step (d): reducing the target value of the generator-side terminal voltage by ΔU, and when the generator-side terminal voltage is stable and the given torque value is T0, determining whether the present value of the generator-side current is smaller than a previous value of the generator-side current, wherein when the present value of the generator-side current is not smaller than the previous value of the generator-side current, the target value of the generator-side terminal voltage is determined as the optimal value of the generator-side terminal voltage, or, when the present value of the generator-side current is smaller than the previous value of the generator-side current, step (d) is repeated; and

step (e): increasing the target value of the generator-side terminal voltage by ΔU, and when the generator-side terminal voltage is stable and the given torque value is T0, determining whether the present value of the generator-side current is smaller than the previous value of the generator-side current, wherein when the present value of the generator-side current is not smaller than the previous value of the generator-side current, the target value of the generator-side terminal voltage is determined as the optimal value of the generator-side terminal voltage or, when the present value of the generator-side current is smaller than the previous value of the generator-side current, step (e) is repeated,

wherein ΔU is greater than 0.

5. The controller according to claim 4 , wherein setting the target value of the generator-side terminal voltage comprises:

when the optimal value of the generator-side terminal voltage exceeds the upper limit of the generator-side terminal voltage, setting the target value of the generator-side terminal voltage to be equal to the upper limit of the generator-side terminal voltage.

6. The controller according to claim 4 , wherein setting the target value of the generator-side terminal voltage comprises:

when the optimal value of the generator-side terminal voltage does not exceed the upper limit of the generator-side terminal voltage, setting the target value of the generator-side terminal voltage to be equal to the optimal value of the generator-side terminal voltage.

7. The controller according to claim 4 , wherein determining the upper limit of the generator-side terminal voltage further comprises:

determining the upper limit of the generator-side terminal voltage further based on at least one of a preset maximum availability of a voltage of the DC bus, a voltage loss corresponding to a dead time of an Insulate-Gate Bipolar Transistor (IGBT) module in a generator-side rectifier unit of the converter, or an on-state voltage drop of the IGBT module in the generator-side rectifier unit of the converter.

8. A computer-readable storage medium having computer programs stored thereon, wherein the computer programs, when executed by a processor, implement a method for controlling a generator-side terminal voltage of a converter, the method comprising:

determining an upper limit of the generator-side terminal voltage based on a present voltage value of a direct-current (DC) bus of the converter, wherein the generator-side terminal voltage is a voltage of an output terminal of a generator, and the output terminal of the generator is connected to the converter;

determining an optimal value of the generator-side terminal voltage from a preset optimal search interval, wherein the optimal value minimizes a present value of a generator-side current when compared with other values in the preset optimal search interval, wherein the generator-side current is a current of the output terminal of the generator; and

setting a target value of the generator-side terminal voltage based on the upper limit of the generator-side terminal voltage and the optimal value of the generator-side terminal voltage, wherein the target value is used to obtain a control reference value of the generator-side terminal voltage,

wherein determining the optimal value of the generator-side terminal voltage comprises:

determining whether a present value of the generator-side terminal voltage falls into the preset optimal search interval; and

responsive to the present value of the generator-side terminal voltage falling into the preset optimal search interval, searching in the preset optimal search interval for the optimal value of the generator-side terminal voltage that minimizes the present value of the generator-side current; and

wherein searching in the preset optimal search interval for the optimal value of the generator-side terminal voltage that minimizes the present value of the generator-side current comprises:

step (a): setting the target value of the generator-side terminal voltage to an initial value, and obtaining a value I0 of the generator-side current and a given torque value T0 of the generator after the generator-side terminal voltage is stable;

step (b): updating the target value of the generator-side terminal voltage as a sum of the initial value and ΔU, and when the generator-side terminal voltage is stable and the given torque value is T0, determining whether a value I1 of the generator-side current is less than I0, wherein when I1 is greater than I0, step (c) is performed, or, when I1 is less than I0, step (e) is performed;

step (c): updating the target value of the generator-side terminal voltage as a difference between the initial value and ΔU, and when the generator-side terminal voltage is stable and the given torque value is T0, determining whether a value I2 of the generator-side current is less than I0, wherein when I2 is greater than I0, the initial value is determined as the optimal value of the generator-side terminal voltage that minimizes the present value of the generator-side current, or, when I2 is less than I0, step (d) is performed;

step (d): reducing the target value of the generator-side terminal voltage by ΔU, and when the generator-side terminal voltage is stable and the given torque value is T0, determining whether the present value of the generator-side current is smaller than a previous value of the generator-side current, wherein when the present value of the generator-side current is not smaller than the previous value of the generator-side current, the target value of the generator-side terminal voltage is determined as the optimal value of the generator-side terminal voltage, or, when the present value of the generator-side current is smaller than the previous value of the generator-side current, step (d) is repeated; and

step (e): increasing the target value of the generator-side terminal voltage by ΔU, and when the generator-side terminal voltage is stable and the given torque value is T0, determining whether the present value of the generator-side current is smaller than the previous value of the generator-side current, wherein when the present value of the generator-side current is not smaller than the previous value of the generator-side current, the target value of the generator-side terminal voltage is determined as the optimal value of the generator-side terminal voltage or, when the present value of the generator-side current is smaller than the previous value of the generator-side current, step (e) is repeated, wherein ΔU is greater than 0.

9. The computer-readable storage medium according to claim 8 , wherein setting the target value of the generator-side terminal voltage comprises:

when the optimal value of the generator-side terminal voltage exceeds the upper limit of the generator-side terminal voltage, setting the target value of the generator-side terminal voltage to be equal to the upper limit of the generator-side terminal voltage.

10. The computer-readable storage medium according to claim 8 , wherein setting the target value of the generator-side terminal voltage comprises:

when the optimal value of the generator-side terminal voltage does not exceed the upper limit of the generator-side terminal voltage, setting the target value of the generator-side terminal voltage to be equal to the optimal value of the generator-side terminal voltage.

11. The computer-readable storage medium according to claim 8 , wherein determining the upper limit of the generator-side terminal voltage further comprises:

determining the upper limit of the generator-side terminal voltage further based on at least one of a preset maximum availability of a voltage of the DC bus, a voltage loss corresponding to a dead time of an Insulate-Gate Bipolar Transistor (IGBT) module in a generator-side rectifier unit of the converter, or an on-state voltage drop of the IGBT module in the generator-side rectifier unit of the converter.