JP2018061376A - Auxiliary power supply apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize the output voltage of an inverter device.SOLUTION: An auxiliary power supply apparatus 10 according to the present invention comprises an inverter device 14 for converting a DC voltage supplied from a DC power supply to an AC voltage, a filter capacitor 12 connected to the input side of the inverter device 14 in parallel with the inverter device 14, and a control circuit 16 for setting a filtered FC (Filter Capacitor) voltage so as to follow the FC voltage and controlling the inverter device 14 on the basis of the set filtered FC voltage. The control circuit 16, when the difference D between the filtered FC voltage and the FC voltage is within a predetermined range, causes the filtered FC voltage to follow the FC voltage at a speed according to a predetermined filter constant T, and, at the time point when the difference D becomes out of the predetermined range, sets the FC voltage at that time point is set as the filtered FC voltage.SELECTED DRAWING: Figure 1

Description

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

  For an electric vehicle that operates by supplying power from an overhead wire, an auxiliary power supply device that converts a DC voltage (overhead voltage) supplied from the overhead wire into an AC voltage and supplies it to a load circuit such as an air conditioner or lighting device in the electric vehicle Is mounted (see, for example, Patent Document 1).

  The auxiliary power supply device includes an inverter device that receives a DC voltage supplied from an overhead wire, converts the input DC voltage into an AC voltage, and outputs the AC voltage. On the input side of the inverter device, a DC filter capacitor for suppressing harmonic current and the like is connected in parallel. The input voltage of the inverter device, that is, the overhead line voltage is constantly changing (fluctuating), and the voltage of the DC filter capacitor (hereinafter referred to as the FC voltage) is also constantly changed by the change of the overhead line voltage. As shown in FIG. 4, the control circuit for controlling the inverter device usually has a constant voltage (hereinafter, referred to as “the constant frequency”) within a predetermined period (within the control cycle) with respect to an actual FC voltage that constantly changes (fluctuates). (Referred to as an FC voltage with a filter), and the inverter device is controlled based on the set FC voltage with a filter.

The FC voltage with filter is usually set based on the following equation (1). In equation (1), x _k indicates the actual FC voltage, y _k indicates the FC voltage with filter, y _k-1 indicates the FC voltage with filter one period before, τ indicates the control period, and T ₁ indicates a constant called a filter constant.

As can be seen from equation (1), the filtered FC voltage is a value obtained by multiplying the difference between the actual FC voltage and the filtered FC voltage one cycle before by a value (τ / T ₁ ) corresponding to the filter constant T _1. Is added to the FC voltage with filter one cycle before. According to Expression (1), the FC voltage with filter can be made to follow the actual FC voltage at a speed according to the filter constant T ₁ . By setting the FC voltage with a filter using such a filter constant T ₁ , the inverter device can be controlled based on a stable voltage value.

JP2015-220890A

  The change in the overhead line voltage includes a phenomenon called a vibration in which the voltage increases or decreases in a small range and a phenomenon called a fluctuation in which the voltage increases or decreases in a range larger than the vibration.

As described above, the FC voltage with filter follows the actual FC voltage at a speed according to the filter constant T ₁ . In the case of vibration, since the overhead voltage, that is, the width in which the FC voltage increases or decreases is small, the FC voltage with filter can follow the FC voltage relatively quickly. On the other hand, in the case of fluctuation, since the width of increase / decrease of the overhead line voltage (FC voltage) is large, it takes time to follow the FC voltage with filter to the FC voltage, and the difference between the FC voltage with filter and the FC voltage is Large state will last for a long time. In such a state, there arises a problem that the output of the auxiliary power supply device becomes unstable.

  The objective of this invention is providing the auxiliary power supply device which can aim at the stabilization of an output voltage which solves the subject mentioned above.

  In order to solve the above-described problem, an auxiliary power supply according to the present invention is an auxiliary power supply that converts a DC voltage supplied from a DC power supply into an AC voltage and supplies the AC voltage to a load circuit, and is supplied from the DC power supply. An inverter device that converts a DC voltage into an AC voltage, a filter capacitor connected in parallel to the inverter device on the input side of the inverter device, and an FC with a filter so as to follow the FC voltage that is the voltage of the filter capacitor A control circuit configured to set a voltage and control the inverter device based on the set FC voltage with filter, wherein the control circuit has a difference between the FC voltage with filter and the FC voltage within a predetermined range. In the case of the above, the FC voltage with filter follows the FC voltage at a speed according to a predetermined filter constant, and the difference There when outside the predetermined range, sets the FC voltage at said time point as the FC voltage with said filter.

  According to the auxiliary power supply device of the present invention, the output voltage can be stabilized.

It is a figure which shows the structure of the auxiliary power supply device which concerns on one Embodiment of this invention. It is a figure for demonstrating the PWM control by the control circuit shown in FIG. It is a figure for demonstrating the PWM control by the control circuit shown in FIG. It is a figure which shows the example of a setting of FC voltage with a filter by the control circuit shown in FIG. It is a figure which shows the example of a setting of FC voltage with a filter by the control circuit shown in FIG. It is a figure for demonstrating FC voltage and FC voltage with a filter.

  Embodiments of the present invention will be described below.

  FIG. 1 is a diagram showing a configuration 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, for example, an electric vehicle that operates by supplying power from the overhead line 1 that is a DC power source, converts a DC voltage supplied from the overhead line 1 into an AC voltage, and loads a load circuit 2 (air conditioner, lighting device, etc. in an electric vehicle).

  The auxiliary power supply device 10 shown in FIG. 1 includes a DC filter reactor 11, a DC filter capacitor 12 (filter capacitor), a voltage measurement unit 13, an inverter device 14, an AC filter / transformer unit 15, and a control circuit 16. Prepare.

  The DC filter reactor 11 has one end connected to the overhead wire 1 and the other end connected to one end of the DC filter capacitor 12. The DC filter capacitor 12 has one end connected to the other end of the DC filter reactor 11 and the other end grounded. The DC filter capacitor 12 is connected in parallel to the inverter device 14 on the input side of the inverter device 14 as will be described later. The DC filter reactor 11 and the DC filter capacitor 12 operate as a filter that suppresses the harmonic current that flows from the overhead wire 1 to the ground via the inverter device 14.

  The voltage measurement unit 13 measures the voltage (FC voltage) of the DC filter capacitor 12 and outputs the measurement result to the control circuit 16.

  The inverter device 14 converts the DC voltage input from the overhead wire 1 through the DC filter reactor 11 and the DC filter capacitor 12 into an AC voltage and outputs the AC voltage to the AC filter / transformer unit 15. The inverter device 14 includes semiconductor switches 141-1 to 144-4. Hereinafter, the semiconductor switches 141-1 to 144-4 are referred to as semiconductor switches 141 when they are not distinguished. The semiconductor switch 141 is configured by connecting a diode in reverse parallel to a switching element such as an IGBT (Insulated Gate Bipolar Transistor).

  The semiconductor switch 141-1 and the semiconductor switch 141-2 are connected in series, and the semiconductor switch 141-3 and the semiconductor switch 141-4 are connected in series. One end of the series body composed of the semiconductor switch 141-1 and the semiconductor switch 141-2 is connected to one end of the DC filter capacitor 12, and the other end is connected to the other end of the DC filter capacitor 12. One end of the series body composed of the semiconductor switch 141-3 and the semiconductor switch 141-4 is connected to one end of the DC filter capacitor 12, and the other end is connected to the other end of the DC filter capacitor 12. Thus, the DC filter capacitor 12 is connected in parallel to the input side of the inverter device 14. Further, the connection point between the semiconductor switch 141-1 and the semiconductor switch 141-2 and the connection point between the semiconductor switch 141-3 and the semiconductor switch 141-4 are connected to the AC filter / transformer unit 15.

  According to the inverter device 14 having such a configuration, by controlling the switching of each semiconductor switch 141, the DC voltage input from the overhead wire 1 through the DC filter reactor 11 and the DC filter capacitor 12 is converted into an AC voltage. Then, the data can be output from the connection point between the semiconductor switch 141-1 and the semiconductor switch 141-2 and the connection point between the semiconductor switch 141-3 and the semiconductor switch 141-4.

  The AC filter / transformer unit 15 smoothes the AC voltage output from the inverter device 14, converts the AC voltage to an AC voltage having a desired magnitude, and outputs the AC voltage to the load circuit 2.

  The control circuit 16 sets the FC voltage with a filter based on the measurement result of the FC voltage by the voltage measuring unit 13, and controls on / off of the semiconductor switch 141 of the inverter device 14 based on the set FC voltage with the filter ( A control signal (PWM signal) for PWM (Pulse Width Modulation) control is output to each semiconductor switch 141.

  2A and 2B are diagrams for explaining PWM control based on the filtered FC voltage by the control circuit 16, FIG. 2A shows a state where the filtered FC voltage is larger than the actual FC voltage, and FIG. The FC voltage with a filter is smaller than the actual FC voltage.

  The control circuit 16 compares the command value for instructing the output voltage of the inverter device 14 with a carrier wave (for example, a triangular wave) corresponding to the value of the FC voltage with filter, and if the carrier wave is smaller than the command value, the logic level is A High (H) PWM signal is output. If the carrier wave is equal to or greater than the command value, a PWM signal having a logic level of Low (L) is output.

  As shown in FIG. 2A, when the FC voltage with filter is larger than the actual FC voltage, the period when the logic level of the PWM signal is L (period when the semiconductor switch 141 is off) is set to the actual FC voltage value. It becomes longer than the case where the corresponding carrier wave and the command value are compared. That is, the duty ratio becomes small. When the duty ratio decreases, the output voltage of the inverter device 14 decreases, and the outflow of power to the load circuit 2 decreases. As a result, the actual FC voltage tends to increase.

  On the other hand, as shown in FIG. 2B, when the FC voltage with filter is smaller than the actual FC voltage, the carrier wave and the command value corresponding to the actual FC voltage value during the period when the logical level of the PWM signal is L It becomes shorter than the case of comparing. That is, the duty ratio increases. As the duty ratio increases, the output voltage of the inverter device 14 increases and the power outflow to the load circuit 2 increases. As a result, the actual FC voltage tends to decrease.

  As described above, when there is a difference between the actual FC voltage and the FC voltage with a filter, the FC voltage easily rises and falls due to this difference. Here, as described above, in the case of vibration in which the FC voltage increases or decreases in a small range, the FC voltage with filter can follow the actual FC voltage relatively quickly. When the voltage fluctuates, it takes time for the filtered FC voltage to follow the FC voltage. In this case, the state where the difference between the actual FC voltage and the FC voltage with filter is large continues for a long time, and the output voltage of the inverter device 14 becomes unstable during that period.

  Therefore, in the present embodiment, when vibration occurs, the control circuit 16 causes the FC voltage with filter to gradually follow the FC voltage (follows according to the equation (1)), and the fluctuation is considered to have occurred. In some cases, the FC voltage with filter is immediately followed by the FC voltage.

  Specifically, the control circuit 16 determines whether or not the difference D between the filtered FC voltage (filtered FC voltage one sample before) and the actual FC voltage is within a predetermined range. When the difference D is within the predetermined range, the control circuit 16 determines that vibration has occurred, and causes the FC voltage with filter to follow the actual FC voltage according to the equation (1). On the other hand, when the difference D is not within the predetermined range, the control circuit 16 determines that a change has occurred. In this case, the control circuit 16 sets the FC voltage at the time of determining that the difference D is not within the predetermined range as the FC voltage with filter. Therefore, when it is considered that the fluctuation has occurred, the FC voltage with filter can immediately follow the FC voltage. Therefore, the difference D between the actual FC voltage and the FC voltage with filter is large, and it is possible to prevent a state where the output of the inverter device 14 is unstable for a long time.

  3A and 3B are diagrams showing examples of setting of the FC voltage with filter by the control circuit 16, and FIG. 3A shows an example of setting of the FC voltage with filter when the vibration in which the FC voltage is increased or decreased in small increments occurs. FIG. 3B is a diagram illustrating a setting example of the FC voltage with a filter when the fluctuation in which the FC voltage greatly increases and decreases over a long time occurs.

  The control circuit 16 determines whether or not the difference D between the filtered FC voltage and the actual FC voltage is within a predetermined range. Specifically, the control circuit 16 determines whether or not −Th ≦ D ≦ Th, where Th is a preset limiter value. The limiter value Th is such that vibration and fluctuation can be distinguished, that is, −Th ≦ D ≦ Th in the case of vibration, and D <0 if the difference D <0 in the case of fluctuation. -Th, and if D> 0, a value such that Th <D is set.

  Therefore, in the case of vibration, as shown in FIG. 3A, −Th ≦ D ≦ Th. In this case, the control circuit 16 causes the FC voltage with filter to follow the actual FC voltage according to the equation (1).

  On the other hand, it is assumed that the fluctuation occurs and the FC voltage greatly increases from time T1 to time T3 as shown in FIG. 3B.

  In this case, in the conventional method in which the FC voltage with filter follows the actual FC voltage according to Equation (1), the FC voltage with filter is gradually increased from time T1 as shown in FIG. The FC voltage can be matched to the actual FC voltage.

  On the other hand, in the method according to the present embodiment (this method), when D (<0) <− Th at time T2 after time T1 and before time T3, the control circuit 16 As shown in 3B, the FC voltage at that time is set as a new FC voltage with a filter. Therefore, the difference D is zero. Thereafter, the FC voltage gradually increases until time T3. However, since −Th ≦ D ≦ Th, the control circuit 16 causes the filtered FC voltage to follow the actual FC voltage according to the equation (1).

  Here, in this method, when the difference D is out of the predetermined range (time T2 in FIG. 3B), the FC voltage at that time is set as the FC voltage with a filter. Therefore, in this method, compared with the conventional method, after time T2, as in the conventional method, even if the FC voltage with a filter follows the FC voltage according to the equation (1), at time T4 prior to time T5. The FC voltage with filter can be matched with the FC voltage. Therefore, even when the fluctuation occurs, the difference D between the FC voltage and the filtered FC voltage is large, and it is possible to prevent the output of the inverter device 14 from being unstable for a long period.

As described above, according to the present embodiment, the auxiliary power device 10 includes the inverter device 14 that converts the DC voltage supplied from the overhead line 1 that is a DC power source into the AC voltage, and the inverter device 14 on the input side of the inverter device 14. And the DC filter capacitor 12 connected in parallel with each other, and the FC voltage with a filter set so as to follow the FC voltage that is the voltage of the DC filter capacitor 12, and the inverter device 14 is controlled based on the set FC voltage with filter. And a control circuit 16. When the difference D between the FC voltage with filter and the FC voltage is within a predetermined range, the control circuit 16 follows the FC voltage with filter at the speed corresponding to the predetermined filter constant T _1. When the difference D is out of the predetermined range, the FC voltage at that time is set as the FC voltage with filter.

  Therefore, when the difference D is out of the predetermined range and the fluctuation is considered to have occurred, the FC voltage with filter can be made to follow the FC voltage at that time. It is possible to prevent a state in which the output of the inverter device 14 is unstable and the output of the inverter device 14 from being unstable for a long period of time.

  Although the present invention has been described based on the drawings and 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, functions included in each block or the like can be rearranged so that there is no logical contradiction, and a plurality of blocks can be combined into one or divided.

1 Overhead Line 2 Load Circuit 10 Auxiliary Power Supply Device 11 DC Filter Reactor 12 DC Filter Capacitor 13 Voltage Measurement Unit 14 Inverter Device 141 Semiconductor Switch 15 AC Filter / Transformer Unit

Claims (1)

An auxiliary power supply device that converts a DC voltage supplied from a DC power source into an AC voltage and supplies the converted voltage to a load circuit,
An inverter device for converting a DC voltage supplied from the DC power source into an AC voltage;
On the input side of the inverter device, a filter capacitor connected in parallel to the inverter device,
A control circuit that sets an FC voltage with a filter so as to follow an FC voltage that is a voltage of the filter capacitor, and controls the inverter device based on the set FC voltage with a filter;
When the difference between the FC voltage with filter and the FC voltage is within a predetermined range, the control circuit converts the FC voltage with filter into the FC voltage at a speed according to a predetermined filter constant. The auxiliary power supply device is characterized in that when the difference is outside the predetermined range, the FC voltage at that time is set as the FC voltage with filter.

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