JP6713367B2 - Auxiliary power supply - Google Patents

Description

The present invention relates to an auxiliary power supply device that converts DC power into AC power and supplies the AC power to a load.

Generally, an electric vehicle that operates by receiving power supply from an overhead line has an auxiliary power supply device that converts direct-current power supplied from the overhead line into alternating-current power by an inverter and supplies it to a load such as an air conditioner or a lighting device in the electric vehicle. It is installed.

In the auxiliary power supply device as described above, a large inrush current (a current much larger than that in a steady state) may flow when starting a load such as a compressor of an air conditioner. When an inrush current flows, especially in a 600 V DC overhead line, the input current to the inverter fluctuates significantly, and the low-frequency component (30 Hz, etc.) of the return line current (the current taken from the overhead line returns to the substation from the rail). ) May appear as noise. Since such a low frequency component of the return current causes a malfunction of the traffic signal, it is required to suppress the peak value of the inrush current and reduce the low frequency component of the return current.

Therefore, Patent Document 1 discloses a technique of suppressing a voltage command instructing the output voltage of the inverter when the rate of change of the output current of the inverter exceeds a predetermined threshold value. According to this technique, when the rate of change of the output current of the inverter exceeds a predetermined threshold value, it is possible to suppress the inrush current by suppressing the voltage command.

JP, 2010-239686, A

In the suppression of the voltage command as described above, the difference between the output current of the inverter and the preset limiter setting value for preventing the output current of the inverter from suddenly changing abruptly is obtained. Then, the voltage command is suppressed by subtracting the voltage corresponding to the control value obtained by the proportional-plus-integral control (PI control) such that the calculated difference becomes zero, from the voltage command.

Normally, the limiter setting value described above is a fixed value. Therefore, when the steady load is small, the output current of the inverter may not reach the limiter set value even if an inrush current occurs, and in this case, the inrush current cannot be suppressed.

An object of the present invention is to solve the above problems and to provide an auxiliary power supply device capable of suppressing the inrush current even when the steady load is small.

In order to solve the above problems, an auxiliary power supply device according to the present invention is an auxiliary power supply device for an electric vehicle that includes an inverter that converts DC power supplied from an overhead wire into AC power and outputs the AC power to a load. A setting unit for setting a limit value for limiting the output voltage of the inverter according to the steady value of the output current of the inverter, and a control unit for controlling the operation of the inverter according to the limit value set by the setting unit. And

Further, in order to solve the above-mentioned problems, in the auxiliary power supply device according to the present invention, it is preferable that the control unit limits a voltage command instructing an output voltage of the inverter according to the limit value.

According to the auxiliary power supply device of the present invention, it is possible to suppress the inrush current even when the steady load is small.

It is a figure which shows the structural example of the auxiliary power supply device which concerns on one Embodiment of this invention. FIG. 3 is a diagram showing an example of setting limiter setting values by the setting unit shown in FIG. 1. FIG. 3 is a diagram showing a configuration example of a control circuit included in the setting unit shown in FIG. 1. It is a figure which shows the structural example of the setting part shown in FIG. FIG. 2 is a diagram showing a main configuration of a control unit shown in FIG. 1. It is a figure which shows an example of the waveform of the output current of the inverter shown in FIG. It is a figure which shows an example of the waveform of the output current of the inverter shown in FIG.

Hereinafter, embodiments of the present invention will be described.

FIG. 1 is a diagram showing a configuration example of an auxiliary power supply device 10 according to an embodiment of the present invention. The auxiliary power supply device 10 according to the present embodiment is mounted on an electric vehicle that operates by receiving electric power from an overhead line, converts DC power supplied from the overhead line into AC power, and air conditioners and lighting devices in the electric vehicle. Output to the load.

The auxiliary power supply device 10 shown in FIG. 1 includes an inverter 11, a setting unit 12, and a control unit 13.

Under the control of the control unit 13, the inverter 11 converts the DC power supplied from the overhead wire into AC power and supplies the AC power to a load in the electric vehicle.

The setting unit 12 sets a limiter setting value ilmt, which is a limit value for limiting the output voltage of the inverter 11, according to the output current of the inverter 11. Specifically, the setting unit 12 sets the limiter setting value ilmt stepwise according to the steady value of the output current of the inverter 11.

FIG. 2 is a diagram showing an example of the limiter setting value ilmt set by the setting unit 12.

In FIG. 2, IoutRms represents the effective value of the output current of the inverter 11. Control logic (ILIM1_M to ILIM16_M) is associated with each of the plurality of limiter setting values ilmt(c). Each control logic is established when the effective value IoutRms of the output current of the inverter 11 is equal to or larger than the corresponding ON value (a) for a predetermined time or more, and the effective value IoutRms of the output current of the inverter 11 is corresponding to the OFF value for a predetermined time or more. When the value is less than or equal to the value (b<a), it is not satisfied. Therefore, for example, when the effective value IoutRms of the output current of the inverter 11 is a predetermined time (for example, 0.5 seconds) or more and a1 [Arms] or more, the control logic ILIM1_M is established. Further, when the effective value IoutRms of the output current of the inverter 11 is equal to or more than a predetermined time (for example, 0.5 seconds) and is equal to or less than b1 (<a1) [Arms], the control logic ILIM1_M is not established. In this way, the setting unit 12 has a plurality of stages of control logic and associates each control logic with the limiter setting value ilmt. In FIG. 2, a1<a2<... <a15<a16 and c0<c1<... <c15<c16. Further, the value of a in each stage is smaller than the value of b in the subsequent stage.

The control logic as described above can be realized by the control circuit 120 shown in FIG. 3, for example. In FIG. 3, the control circuit 120 for realizing the control logic of the control logic ILIM11_M will be described as an example.

The control circuit 120 shown in FIG. 3 includes on-timer delays (ONTD: On Timer Delay) 121 and 122 and a switch 123.

The on-timer delay 121 turns on the switch 123 when the output current Iout of the inverter 11 is input and the effective value IoutRms of the output current Iout becomes a predetermined time or more (for example, 0.5 seconds or more) and a predetermined value (a11) or more. Therefore, the switching signal ILM11_ON_T is output to the switch 123.

The on-timer delay 122 turns off the switch 123 when the output current Iout of the inverter 11 is input and the effective value IoutRms of the output current Iout becomes a predetermined time or more (for example, 0.5 seconds or more) and a predetermined value (b11) or less. Therefore, the switching signal ILM11_OFF_T is output to the switch 123.

The switch 123 is turned on when the switching signal ILM11_ON_T is output from the on-timer delay 121, and outputs the signal ILM11_M indicating that the control logic ILIM11_M is established. The switch 123 is turned off when the switching signal ILM11_OFF_T is output from the on-timer delay 122. When the switch 123 is turned off, the output of the signal ILM11_M is stopped and the control logic ILIM11_M is not established.

As shown in FIG. 4, the setting unit 12 includes the control circuit 120 (control circuits 120-1 to 120-16) shown in FIG. 3 for each control logic shown in FIG. Then, the setting unit 12 sets, as the limiter set value ilmt, a value associated with the control logic having the highest number of stages among the control logics to which the signal indicating that the condition is satisfied is output.

Referring back to FIG. 1, the control unit 13 controls the operation of the inverter 11 according to the limiter setting value ilmt set by the setting unit 12. Specifically, as shown in FIG. 5, the control unit 13 subtracts a value according to the limiter set value ilmt set by the setting unit 12 from the voltage command v that instructs the output voltage of the inverter 11, and after the synthesis, The voltage command vo is generated. Then, the control unit 13 controls the inverter 11 according to the combined voltage command vo.

The configuration of the control unit 13 will be described with reference to FIG. It is a diagram showing a configuration of a main part of the control unit 13, and describes a configuration for generating a combined voltage command vo, and another function of the control unit 13, for example, a function of controlling the inverter 11. The description of the configuration related to, etc. is omitted.

The control unit 13 illustrated in FIG. 5 includes a subtractor 131, a PI control unit 132, a limiter 133, and an adder 134.

The subtractor 131 subtracts the output current Iout of the inverter 11 from the limiter setting value ilmt set by the setting unit 12, and outputs it to the PI control unit 132.

The PI control unit 132 outputs to the limiter 133 a control value obtained by proportional-plus-integral control (PI control) such that the difference between the limiter setting value ilmt output from the subtractor 131 and the output current Iout of the inverter 11 becomes zero. To do.

The limiter 133 outputs a correction value v1 for correcting the voltage command v of the inverter 11 according to the control value output from the PI control unit 132. Here, the limiter 133 outputs a value of 0 or less as the correction value v1, and the larger the control value output from the PI controller 132 is (the larger the difference between the limiter setting value ilmt and the output current Iout of the inverter 11 is. Output), a large value is output in the negative direction.

The adder 134 adds (combines) the voltage command v and the correction value v1 output from the limiter 133, and outputs the combined voltage command vo. The inverter 11 is controlled according to the combined voltage command vo.

As described above, the limiter 133 outputs a larger correction value v1 in the negative direction as the difference between the limiter setting value ilmt and the output current Iout of the inverter 11 is larger. That is, the larger the difference between the limiter setting value ilmt and the output current Iout of the inverter 11, the larger the value is subtracted from the voltage command v. Therefore, even when the inrush current flows and the output current Iout of the inverter 11 increases, the output voltage of the inverter 11 can be suppressed, and as a result, the inrush current can be suppressed. Here, in the present embodiment, the limiter setting value ilmt is set according to the steady value of the output current Iout of the inverter 11. Therefore, even when the steady load is small and the steady current is small, it is possible to set the limiter setting value ilmt according to the steady current, so that it is possible to suppress the inrush current.

FIG. 6 is a diagram showing an example of the waveform of the output current Iout of the inverter 11 when the present invention is not applied. In the following, a case will be described as an example where two air conditioners each have two compressors and the compressors of each air conditioner are sequentially activated.

At time t11, it is assumed that the first compressor CP11 of the first air conditioner is activated from the steady state. Then, it is assumed that an inrush current flows and the output current Iout of the inverter 11 sharply increases in response to the activation of the compressor CP11.

After that, at time t12, it is assumed that the inrush current converges and the output current Iout of the inverter 11 enters a steady state. The steady-state value of the output current Iout of the inverter 11 in this case is larger than the steady-state value of the output current Iout of the inverter 11 before the compressor CP11 is started (before the time t11).

Next, at time t14, it is assumed that the second compressor CP12 of the first air conditioner is activated. Then, it is assumed that an inrush current flows and the output current Iout of the inverter 11 sharply increases in response to the activation of the compressor CP12.

After that, at time t15, it is assumed that the inrush current converges and the output current Iout of the inverter 11 enters a steady state. The steady-state value of the output current Iout of the inverter 11 in this case is larger than the steady-state value of the output current Iout of the inverter 11 before the compressor CP12 is started (before the time t14).

Next, at time t17, it is assumed that the first compressor CP21 of the second air conditioner is activated. Then, it is assumed that an inrush current flows in response to the activation of the compressor CP21 and the output current Iout of the inverter 11 sharply increases.

After that, at time t18, it is assumed that the inrush current converges and the output current Iout of the inverter 11 enters a steady state. The steady-state value of the output current Iout of the inverter 11 in this case is larger than the steady-state value of the output current Iout of the inverter 11 before the compressor CP21 is started (before the time t17).

Next, at time t19, it is assumed that the second compressor CP22 of the second air conditioner is activated. Then, it is assumed that an inrush current flows and the output current Iout of the inverter 11 sharply increases in response to the activation of the compressor CP22.

After that, at time t20, it is assumed that the inrush current converges and the output current Iout of the inverter 11 enters a steady state. The steady-state value of the output current Iout of the inverter 11 in this case is larger than the steady-state value of the output current Iout of the inverter 11 before the compressor CP22 is started (before the time t19).

As shown in FIG. 6, the steady-state current value increases as the driving load increases. Further, assuming that the increase amount of the output current Iout of the inverter 11 due to the rush current is substantially equal, the peak value of the rush current increases as the driving load increases. In order to suppress the inrush current and reduce the low frequency component of the return current, as shown in FIG. 6, it is necessary to suppress the output current Iout of the inverter 11 before the inrush current reaches its peak.

Here, as shown in FIG. 6, when the fixed limiter setting value ilmt(Fix) is used, even if the inrush current occurs in the state where the steady current is small (for example, the state at time t11), the output of the inverter 11 is reduced. The current Iout may not reach the limiter setting value ilmt(Fix). In this case, the limiter current cannot be suppressed. Therefore, it is conceivable to reduce the limiter setting value ilmt(Fix) so that the inrush current generated when the steady current is small can be suppressed. However, since the upper limit of the output of the inverter 11 is set by the limiter setting value ilmt(Fix), if the limiter setting value ilmt(Fix) is made small, the output obtained from the inverter 11 also becomes small.

On the other hand, in the present embodiment, as shown in FIG. 7, the limiter set value ilmt is set according to the output current Iout of the inverter 11 (steady value of the output current Iout). Here, as shown in FIG. 7, when the output current Iout of the inverter 11>the limiter setting value ilmt, the correction value v1 output from the limiter 133 is increased by the difference between the output current Iout and the limiter setting value ilmt. Become. As a result, the voltage command can be instantaneously lowered and the peak value of the output current Iout can be suppressed.

For example, the setting unit 12 sets the limiter setting value ilmt according to the value of the output current Iout of the inverter 11 in the steady state before time t11. The limiter set value ilmt set here is set such that when the inrush current occurs in the steady state before time t11, the output current Iout of the inverter 11 is suppressed before the inrush current reaches its peak. To be done. Therefore, as shown in FIG. 7, the output current Iout of the inverter 11 reaches the limiter setting value ilmt before the inrush current generated at time t11 reaches the peak, and as a result, the output voltage of the inverter 11 is suppressed. Therefore, the inrush current is also suppressed before reaching the peak.

After time t12, when the steady state is reached, at time t13 when a predetermined time (for example, 0.5 seconds) has passed from time t12, the setting unit 12 determines, according to the value of the output current Iout of the inverter 11 at that time. Set the limiter setting value ilmt. The limiter setting value ilmt set at the time t13 is a value such that when the inrush current occurs in the steady state after the time t12, the output current Iout of the inverter 11 is suppressed before the inrush current reaches its peak. Is set. Therefore, the output current Iout of the inverter 11 reaches the limiter setting value ilmt before the inrush current generated at the time t14 reaches the peak, and as a result, the output voltage of the inverter 11 is suppressed. Therefore, the inrush current is also suppressed before reaching the peak.

After time t15, when the steady state is reached, at time t16 when a predetermined time (for example, 0.5 seconds) has elapsed from time t15, the setting unit 12 determines, according to the value of the output current Iout of the inverter 11 at that time. Set the limiter setting value ilmt. The limiter setting value ilmt set at the time t16 is a value such that when the rush current occurs in the steady state after the time t15, the output current Iout of the inverter 11 is suppressed before the rush current reaches its peak. Is set. Therefore, the output current Iout of the inverter 11 reaches the limiter setting value ilmt before the inrush current generated at time t17 reaches the peak, and as a result, the output voltage of the inverter 11 is suppressed. Therefore, the inrush current is also suppressed before reaching the peak.

Hereinafter, similarly, the setting unit 12 sets the limiter setting value ilmt according to the value of the output current Iout of the inverter 11.

As described above, in the present embodiment, the auxiliary power supply device 10 sets the limiter setting value ilmt, which is a limit value for limiting the output voltage of the inverter 11, according to the steady value of the output current Iout of the inverter 11. A unit 12 and a control unit 13 that controls the operation of the inverter 11 according to the limiter setting value ilmt set by the setting unit 12 are provided.

By setting the limiter setting value ilmt according to the value of the output current Iout of the inverter 11, it is possible to suppress the inrush current even when the steady load is small. As a result, it is possible to reduce the low frequency component (noise such as 30 Hz) of the return current. Moreover, by setting the limiter setting value ilmt according to the value of the output current Iout, the upper limit of the output of the inverter 11 is not fixed unlike the case where a fixed limiter setting value ilmt is used.

Although the present invention has been described based on the drawings and the embodiments, it should be noted that those skilled in the art can easily make various variations or modifications based on the present disclosure. Therefore, it should be noted that these variations or modifications are included in the scope of the present invention. For example, the functions included in each block can be rearranged so as not to logically contradict each other, and a plurality of blocks can be combined into one or divided.

10 Auxiliary Power Supply Device 11 Inverter 12 Setting Unit 13 Control Unit 120 Control Circuit 121, 122 On-Timer Delay 123 Switch 131 Subtractor 132 PI Control Unit 133 Limiter 134 Adder

Claims (2)

An auxiliary power supply device for an electric vehicle including an inverter that converts DC power supplied from an overhead wire into AC power and outputs the AC power to a load,
A setting unit for setting a limit value for limiting the output voltage of the inverter according to a steady value of the output current of the inverter,
A control unit that controls the operation of the inverter according to the limit value set by the setting unit, the auxiliary power supply device. The auxiliary power supply device according to claim 1,
The auxiliary power supply device, wherein the control unit limits a voltage command instructing an output voltage of the inverter according to the limit value.

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