JP2020137201A - Electric power conversion apparatus and operation method thereof, as well as vehicle - Google Patents

Abstract

To provide an electric power conversion apparatus that can detect abnormality in a case where there is a possibility in which abnormality occurs in an input voltage monitor circuit.SOLUTION: An electric power conversion apparatus comprises: an electric power converter; an input voltage monitor circuit that monitors input voltage into the electric power converter; a control circuit that controls the electric power converter to response to output voltage of the electric power converter and output of the input voltage monitor circuit and such that output of the electric power converter is a target value; and an abnormality determination circuit that determines whether or not abnormality occurs in either of an output system of the electric power converter and the input voltage monitor circuit on the basis of the output of the input voltage monitor circuit and voltage of a predetermined position in the electric power converter, and that adjusts control of the electric power converter by means of the control circuit according to the determination result.SELECTED DRAWING: Figure 1

Description

This disclosure relates to a power converter and its operating method, as well as a vehicle.

In the power conversion device, when a system accident point occurs on the primary side of the interconnection transformer, a follow-up delay of the secondary side voltage (output voltage of the power conversion device) occurs. It is desirable to reduce the overcurrent as much as possible by further improving the responsiveness in this case.

An example of such a power conversion device is disclosed in Patent Document 1 described later. The power conversion device disclosed in Patent Document 1 normally monitors the input voltage from the system side, adds the value excluding harmonics by a low-pass filter to the switching element of the inverter, and adds it to the control signal of the inverter. By doing so, the switching element of the inverter is fed forward. Furthermore, when this power converter detects a voltage drop on the input side when a system accident point occurs, the voltage detection value and current detection value of the cooperation point with the system and the control voltage deviation for suppressing the fluctuation current of the heel. Has a circuit to estimate. When a system fault point occurs, a control voltage deviation is selected instead of the normal feedforward signal, and the voltage deviation is fedforwarded to the drive signal of the switching element of the inverter.

JP 2018-196190

There is still room for improvement in the power conversion device using the feed forward as disclosed in Patent Document 1. In order to perform feed forward control, it is necessary to monitor the input voltage to the power converter by some kind of circuit. If an abnormality occurs in this circuit, the change in the input voltage cannot be detected, and the output of the power converter may be disturbed. Therefore, if there is a possibility that an abnormality has occurred in the circuit that monitors the input voltage, it is necessary to be able to detect it. Particular attention should be paid when this circuit deteriorates over time. Further, even if an abnormality occurs in this circuit, it is desirable not to stop the operation of the power conversion device.

In particular, recently, the number of vehicles equipped with a power conversion device, such as electric vehicles, is increasing. It is desirable to stabilize the output of the power converter in case the number of electric vehicles increases in the future. Needless to say, it is preferable in terms of vehicle operation that the power converter itself continues to operate in the same manner as usual even when an abnormality occurs in the circuit that monitors the input voltage.

Therefore, the purpose of this disclosure is to provide a power conversion device and an operation method thereof, and a vehicle capable of detecting an abnormality in a circuit that monitors an input voltage from the system side when there is a possibility that an abnormality has occurred. To do.

The power converter according to the first disclosure is a power converter, an input voltage monitor circuit for monitoring the input voltage to the power converter, and a power conversion in response to the output voltage of the power converter and the output of the input voltage monitor circuit. The output system and input voltage of the power converter based on the control circuit that controls the power converter so that the output of the device becomes the target value, the output of the input voltage monitor circuit, and the voltage at a predetermined position in the power converter. It includes an abnormality determination circuit that determines whether or not an abnormality has occurred in any of the monitor circuits and adjusts the control of the power converter by the control circuit according to the determination result.

The second disclosed vehicle includes a vehicle body, a battery provided in the vehicle body that stores and outputs power at a first voltage, and a low battery that is installed in the vehicle body and operates at a second voltage lower than the first voltage. It includes the voltage operating unit and the above-mentioned power conversion device provided in the vehicle body so as to receive the output of the battery as an input, convert it into a second voltage, and supply it to the low voltage operating unit.

The operation method of the power converter of the third disclosure responds to the power converter, the input voltage monitor circuit for monitoring the input voltage to the power converter, and the output voltage and the output of the input voltage monitor circuit of the power converter. , The output system of the power converter based on the control circuit that controls the power converter so that the output of the power converter becomes the target value, the output of the input voltage monitor circuit, and the voltage at the predetermined position in the power converter. And an operation method of the power conversion device including an abnormality determination circuit that determines whether or not an abnormality has occurred in any of the input voltage monitor circuits and adjusts the control of the power converter by the control circuit according to the determination result. The step that the input voltage monitor circuit monitors the input voltage to the power converter and outputs a signal representing the input voltage, the control circuit outputs the signal of the input voltage monitor circuit, and the power converter A step of controlling the power converter so that the output of the power converter becomes a target value in response to the output voltage, a signal output by the input voltage monitor circuit by the abnormality determination circuit, and a predetermined position in the power converter. This includes a step of determining whether or not an abnormality has occurred in either the output system or the input voltage monitor circuit based on the voltage of the above, and adjusting the control of the power converter by the control circuit according to the determination result.

The present invention can be realized not only as a power conversion device provided with such a characteristic processing unit, but also as an operation method of the power conversion device having such a characteristic processing as a step, or such a step. Can be realized as a program for causing a computer to execute. Further, it can be realized as a semiconductor integrated circuit that realizes a part or all of the power conversion device, or can be realized as a system of a vehicle or the like including the power conversion device.

According to this disclosure, when there is a possibility that an abnormality has occurred in the input voltage monitor circuit, it is possible to provide a power conversion device capable of detecting the abnormality, an operation method thereof, and a vehicle.

FIG. 1 is a block diagram showing a configuration of a power conversion device according to the first embodiment. FIG. 2 is a circuit diagram of a voltage conversion unit that performs a process corresponding to voltage conversion in the power conversion device according to the first embodiment. FIG. 3 is a flowchart showing a control structure of a program for controlling the power conversion circuit executed by the control circuit of the power conversion device according to the first embodiment. FIG. 4 is a flowchart showing the control structure of the routine for determining whether or not the sensor for monitoring the input voltage is deteriorated in the flowchart showing the control structure in FIG. FIG. 5 is a diagram schematically showing a schematic configuration of a vehicle according to the second embodiment of the present disclosure, which is equipped with the power conversion device according to the first embodiment. FIG. 6 is a block diagram showing a schematic configuration of hardware of a microcontroller unit that realizes a control circuit of the power conversion device according to the first embodiment.

[Explanation of Embodiments of this Disclosure]
In the following description and drawings, the same parts are given the same reference numbers. Therefore, detailed explanations about them will not be repeated. In addition, at least a part of the embodiments described below may be arbitrarily combined.

(1) The power converter according to the first disclosure responds to a power converter, an input voltage monitor circuit for monitoring the input voltage to the power converter, and an output voltage of the power converter and an output of the input voltage monitor circuit. However, the output of the power converter is based on the output of the control circuit that controls the power converter so that the output of the power converter becomes the target value, the output of the input voltage monitor circuit, and the voltage at a predetermined position in the power converter. It includes an abnormality determination circuit that determines whether or not an abnormality has occurred in either the system or the input voltage monitor circuit and adjusts the control of the power converter by the control circuit according to the determination result.

The control circuit responds to the output voltage of the power converter and the output of the input voltage monitor circuit, and controls the power converter so that the output of the power converter becomes a target value. The abnormality determination circuit determines whether or not an abnormality has occurred in either the output system of the power converter or the input voltage monitor circuit based on the output of the input voltage monitor circuit and the voltage at a predetermined position in the power converter. Then, the control of the power converter by the control circuit is adjusted according to the determination result. When the power converter is controlled by using the output of the input voltage monitor circuit, the control of the power converter may become unstable if an abnormality occurs in the input voltage monitor circuit. However, in this disclosure, an abnormality determination circuit indicates that an abnormality has occurred in either the output system of the power converter or the input voltage monitor circuit based on the output of the input voltage monitor circuit and the voltage at a predetermined position in the power converter. Can be determined. When an abnormality occurs, the abnormality determination circuit adjusts the control of the power converter. Even if an abnormality occurs in the input voltage monitor circuit, the power converter can be adjusted appropriately, so that the operation of the power converter can be stabilized.

(2) Preferably, the abnormality determination circuit has an abnormality in either the output system or the input voltage monitor circuit depending on whether or not a predetermined relationship is established between the output of the input voltage monitor circuit and the voltage at a predetermined position. It includes a determination circuit for determining whether or not it has occurred, and an adjustment circuit for adjusting the control of the power converter by the control circuit according to the determination result of the determination circuit.

There is almost no possibility that an abnormality will occur at the same time in the input voltage monitor circuit and the circuit portion that generates the voltage at a predetermined position. And in the normal state, a predetermined relationship is established between each other. Therefore, the abnormality determination circuit determines whether or not an abnormality has occurred in either the output system or the input voltage monitor circuit depending on whether or not a predetermined relationship is established between the output of the input voltage monitor circuit and the voltage at a predetermined position. Is determined. Even if it is determined that an abnormality has occurred by this determination, it cannot be determined that it is an abnormality of the input voltage monitor circuit. However, when an abnormality occurs in the input voltage monitor circuit, the abnormality can be detected and appropriate measures can be taken.

(3) More preferably, the control circuit uses the output of the input voltage monitor circuit to perform feed-forward control of the switching circuit in the power converter, and the adjustment circuit is said to have caused an abnormality by the abnormality determination circuit. In response to the determination, the feed forward control by the control circuit is stopped.

The output of the input voltage monitor circuit is used for feed forward control of the switching circuit of the power converter. This feedforward control is used to correct the control amount of the feedback control of the power converter using the output of the power converter. Even if the feedforward control is stopped, the feedback control is performed, so that the operation of the power converter does not stop, and the power converter can continue to operate almost normally.

(4) More preferably, the determination circuit monitors the input voltage between the output of the input voltage monitor circuit and the voltage at a predetermined position when the input voltage monitor circuit and the power converter are operating normally. A conversion circuit that converts at least one of the output of the input voltage monitor circuit and the voltage at the predetermined position according to the predetermined conversion formula so that the output of the circuit and the value after conversion with the voltage at the predetermined position are equal. Determines whether an error has occurred in either the output system or the input voltage monitor circuit according to whether the output of the input voltage monitor circuit and the voltage at the predetermined position match after at least one of them has been converted by the conversion circuit. Includes a conversion value comparison circuit.

In the power converter, it is premised that the input voltage and the output voltage are different, and it is not possible to simply compare the two. Therefore, the conversion circuit inputs so that the output of the input voltage monitor circuit and the converted value of the voltage at the predetermined position become equal when the input voltage monitor circuit and the power converter are operating normally. At least one of the output of the voltage monitor circuit and the voltage at a predetermined position is converted according to a predetermined conversion formula. This conversion makes it possible to compare both values. As a result, the converted value comparison circuit can determine whether or not an abnormality has occurred in either the output system or the input voltage monitor circuit.

(5) Preferably, the power converter is a switching circuit including a plurality of switching elements that receive an input voltage as an input and perform switching according to the control of the control circuit, and a transformer in which a primary side coil is connected to the output of the switching circuit. And a rectifier circuit connected to the secondary side coil of the transformer, the rectifier circuit includes a diode for rectifying the output voltage of the transformer, and a predetermined position is the voltage on the cathode side of the diode.

The voltage on the cathode side of the diode of the output system of the power conversion circuit is relatively stable. Therefore, the comparison with the output of the input voltage monitor circuit can be performed stably.

(6) More preferably, the conversion circuit has a _first resistor having a resistance value of R1 having one terminal connected at a predetermined position and the other terminal connected to the input of the conversion value comparison circuit, and a first resistor. is connected between the other terminal and a reference voltage of the first resistance, the resistance value comprises a second resistor and a R _2, according to the first resistor and the second resistor, the voltage dividing ratio in the other terminal, the following Calculated by the formula of

換算回路はさらに、以下の式により、ダイオードのカソード側の電圧Ｖから、入力電圧モニタ回路の出力と比較する入力電圧Ｖ_ＩＮを計算する計算回路を含む。

The conversion circuit further includes a calculation circuit that calculates an input voltage V _IN to be compared with the output of the input voltage monitor circuit from the voltage V on the cathode side of the diode by the following equation.

ただし、Ｎ＝トランスの巻数比、ｄｕｔｙ＝スイッチング回路のスイッチング素子のデューティ比、Ｖｆ＝ダイオードの順方向電圧、１０００はボルトからミリボルトへの単位変換係数を、それぞれ表す。

However, N = the turn ratio of the transformer, duty = the duty ratio of the switching element of the switching circuit, Vf = the forward voltage of the diode, and 1000 represents the unit conversion coefficient from volt to millivolt.

After converting the voltage at a predetermined position with the voltage division ratio obtained by the two resistors, the input voltage can be calculated by the conversion formula of the formula (2). A simple circuit can calculate the value for conversion.

(7) More preferably, the conversion value comparison circuit is used when the absolute value of the difference between the value _VIN calculated by the equation (2) and the output of the input voltage monitor circuit is equal to or greater than a predetermined positive threshold value. , It is determined that an abnormality has occurred in either the output system or the input voltage monitor circuit.

The presence or absence of an abnormality can be determined by a simple index called the absolute value of the difference.

(8) Preferably, in the conversion value comparison circuit, the ratio of the value of the value _VIN calculated by the equation (2) to the output of the input voltage monitor circuit is greater than or equal to the first threshold value greater than 1, or greater than 1. When it is equal to or less than a small second threshold value, it is determined that an abnormality has occurred in either the output system or the input voltage monitor circuit.

The presence or absence of an abnormality can be determined by a simple index called the ratio of two values.

(9) The vehicle according to the second disclosure includes a vehicle body, a battery provided in the vehicle body that stores and outputs electric power at the first voltage, and a second voltage provided in the vehicle body that is lower than the first voltage. And any of the above-mentioned power conversion devices provided in the vehicle body to receive the output of the battery as an input, convert it to a second voltage, and supply it to the low-voltage operating unit. including.

The control circuit responds to the output voltage of the power converter and the output of the input voltage monitor circuit, and controls the power converter so that the output of the power converter becomes a target value. The abnormality determination circuit determines whether or not an abnormality has occurred in either the output system of the power converter or the input voltage monitor circuit based on the output of the input voltage monitor circuit and the voltage at a predetermined position in the power converter. Then, the control of the power converter by the control circuit is adjusted according to the determination result. When the power converter is controlled by using the output of the input voltage monitor circuit, there is a risk that the control of the power converter will be adversely affected if an abnormality occurs in the input voltage monitor circuit. However, in this disclosure, an abnormality determination circuit indicates that an abnormality has occurred in either the output system of the power converter or the input voltage monitor circuit based on the output of the input voltage monitor circuit and the voltage at a predetermined position in the power converter. Can be determined. When an abnormality occurs, the abnormality determination circuit adjusts the control of the power converter. Even if an abnormality occurs in the input voltage monitor circuit, the power converter can be adjusted appropriately, so that the operation of the power converter can be stabilized. Further, by adopting each of the above-mentioned power conversion devices, the above-mentioned effects can be obtained.

(10) The operation method of the power converter according to the third disclosure is the power converter, the input voltage monitor circuit for monitoring the input voltage to the power converter, and the output voltage and input voltage monitor circuit of the power converter. Power conversion based on the control circuit that responds to the output and controls the power converter so that the output of the power converter becomes the target value, the output of the input voltage monitor circuit, and the voltage at a predetermined position in the power converter. Power conversion including an abnormality determination circuit that determines whether or not an abnormality has occurred in either the output system of the device or the input voltage monitor circuit and adjusts the control of the power converter by the control circuit according to the determination result. The operation method of the device is that the input voltage monitor circuit monitors the input voltage to the power converter and outputs a signal representing the input voltage, and the control circuit outputs the signal of the input voltage monitor circuit. In response to the output voltage of the power converter, the step of controlling the power converter so that the output of the power converter becomes the target value, the abnormality determination circuit outputs the signal of the input voltage monitor circuit, and the power converter A step of determining whether or not an abnormality has occurred in either the output system or the input voltage monitor circuit based on the voltage at a predetermined position inside, and adjusting the control of the power converter by the control circuit according to the determination result. And include.

The input voltage monitor circuit monitors the input voltage to the power converter and outputs a signal representing the input voltage. The control circuit responds to the signal output by the input voltage monitor circuit and the output voltage of the power converter, and controls the power converter so that the output of the power converter becomes a target value. The abnormality determination circuit determines whether or not an abnormality has occurred in either the output system or the input voltage monitor circuit based on the signal output by the input voltage monitor circuit and the voltage at a predetermined position in the power converter. The control of the power converter by the control circuit is adjusted according to the determination result. When the power converter is controlled by using the output of the input voltage monitor circuit, there is a risk that the control of the power converter will be adversely affected if an abnormality occurs in the input voltage monitor circuit. However, in this disclosure, an abnormality determination circuit indicates that an abnormality has occurred in either the output system of the power converter or the input voltage monitor circuit based on the output of the input voltage monitor circuit and the voltage at a predetermined position in the power converter. Can be determined. When an abnormality occurs, the abnormality determination circuit adjusts the control of the power converter. Even if an abnormality occurs in the input voltage monitor circuit, the power converter can be adjusted appropriately, so that the operation of the power converter can be stabilized.
[Details of Embodiments of this Disclosure]
A power conversion device according to an embodiment of this disclosure, an operation method thereof, and a specific example of a vehicle will be described below with reference to the drawings. It should be noted that this disclosure is not limited to these examples, and is indicated by the scope of claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

[Embodiment 1]
<Constitution>
FIG. 1 shows a circuit block diagram of the power conversion device 50 according to the first embodiment of the disclosure. With reference to FIG. 1, the power converter 50 is connected to both positive and negative terminals of the DC power supply 60, and is converted into a DC voltage different from the DC voltage from the DC power supply 60 and applied to the load 64. A voltage sensor 66 that measures the voltage on the positive side of the DC power supply 60 and outputs an analog signal that represents the voltage, and an input voltage monitor IC70 that monitors the signal output by the voltage sensor 66 and outputs a digital signal that represents the input voltage ( Integrated Circuit), a voltage sensor 68 that measures the output voltage of the power converter 62 and outputs an analog signal, and a voltage sensor 68 that detects the voltage at a predetermined position in the output system of the power converter 62 and outputs the normal input voltage monitor IC70. A switching element constituting a voltage adjusting circuit 74 that converts the voltage at a predetermined position so as to be equal to the voltage to be performed, and a half bridge circuit 78 that is a switching circuit based on the output of the input voltage monitor IC 70 and the signal from the voltage sensor 68. Includes an MCU (microcontroller unit) 72 that generates and outputs a drive signal of.

The power converter 62 includes a capacitor 90 connected between the positive and negative terminals of the DC power supply 60, a half bridge circuit 78 connected in parallel with the capacitor 90, and a primary side connected to the output side of the half bridge circuit 78. A transformer 80 having a coil, diodes 96 and 98 having an anode connected to the secondary coil of the transformer 80 and a cathode connected to each other, and a reactor 100 having one end connected to the cathode of the diodes 96 and 98. A capacitor 102 connected between the other end of the reactor 100 and the ground potential, and a voltage sensor 104 that detects the voltage on the cathode side of the diode 96 and the diode 98 and outputs an analog signal representing the voltage to the voltage adjustment circuit 74. including. Both terminals of the capacitor 102 are connected to the load 64.

The half-bridge circuit 78 includes MOSFETs (Metal Oxide Semiconductor Field Effect Transistor) 82 and 86 connected in series between the positive and negative terminals of the DC power supply 60, and a body diode 84 and body diodes 84 connected in parallel with these, respectively. Includes 88 and two capacitors 92 and 94 connected in series between the positive and negative electrodes of the DC power supply 60 in parallel with these MOSFETs 82 and 86. The connection nodes of the MOSFETs 82 and 86 and the connection nodes of the capacitors 92 and 94 are connected to both ends of the primary coil of the transformer 80, respectively.

The MCU 72 operates as a program as described later, and outputs a drive signal for driving the MOSFETs 82 and 86 of the half-bridge circuit 78 based on the output of the input voltage monitor IC 70, the voltage adjustment circuit 74, and the voltage sensor 68. The 120 and the abnormality detector 122 for detecting that the input voltage has become an abnormal value based on the output of the input voltage monitor IC 70 and performing necessary processing are realized. A feed forward by the output of the input voltage monitor IC 70 is incorporated in the control of the switching element of the half bridge circuit 78 by the controller 120. In FIG. 1, the analog signal input to the MCU 72 is converted into a digital signal by an analog / digital (A / D) converter (not shown).

The voltage on the cathode side of the diode 98 is relatively stable. Therefore, the voltage value and the output of the input voltage monitor IC 70 can be compared stably. In this embodiment, the voltage sensor 104 is connected to the cathode side of the diode 98. However, in reality, the voltage at any position may be used as long as the relationship with the input voltage can be calculated in the rectifier circuit of the diode 98. For example, the voltage on the anode side of the diode 98 may be used.

The voltage adjusting circuit 74 comprises an analog circuit in this embodiment. FIG. 2 shows a circuit block diagram of the voltage adjusting circuit 74. With reference to FIG. 2, the voltage adjusting circuit 74 divides the voltage of the analog signal output by the voltage sensor 104 and adjusts the voltage so that it is theoretically equal to the voltage of the signal output by the input voltage monitor IC 70. It includes a voltage divider circuit 200 and a filter 202 for removing noise from the output signal of the voltage divider circuit 200 and giving it to the MCU 72.

One end of the voltage dividing circuit 200 is connected to the output of the voltage sensor 104, and the resistance value R ₂ is connected between the first resistor 210 having the resistance value R ₁ and the other end of the resistor 210 and the ground potential. Includes a second resistor 212 with. The connection nodes of resistors 210 and 212 are connected to the input of filter 202.

When the voltage value of the output signal of the theoretical input voltage monitor IC70 and _{R a,} the resistance value _{R 1} and _{R 2} of the resistor 210 and 212 are selected so as to satisfy the following formula (a1).

この値Ｒ_ａを用いると、電圧センサ１０４の出力する電圧Ｖ［Ｖ］から入力電圧モニタＩＣ７０により検出される入力電圧Ｖ_ＩＮ［ｍＶ］は理論的には以下の式（ａ２）により算出される。

Using this value R _a , the input voltage V _IN [mV] detected by the input voltage monitor IC 70 from the voltage V [V] output by the voltage sensor 104 is theoretically calculated by the following equation (a2). ..

ただし、Ｎ＝トランス８０の巻数比、ｄｕｔｙ＝ハーフブリッジ回路７８のＭＯＳＦＥＴ８２および８６のデューティ比、Ｖｆ＝ダイオード９６および９８の順方向電圧を、それぞれ表す。式（ａ２）の右辺の１０００はボルトからミリボルトへの単位変換係数である。このように式（ａ２）により換算された電圧センサ１０４の検出した電圧値と、実際に入力電圧モニタＩＣ７０から得られた値とを比較し、両者が一致しているか否かによって入力電圧モニタＩＣ７０に異常が発生しているか否かを判定する。

However, N = the turn ratio of the transformer 80, duty = the duty ratio of the MOSFETs 82 and 86 of the half-bridge circuit 78, and Vf = the forward voltage of the diodes 96 and 98, respectively. 1000 on the right side of the equation (a2) is a unit conversion coefficient from volt to millivolt. The voltage value detected by the voltage sensor 104 converted by the equation (a2) is compared with the value actually obtained from the input voltage monitor IC 70, and the input voltage monitor IC 70 is determined by whether or not they match. Judge whether or not an abnormality has occurred in.

The MCU 72 shown in FIG. 1 realizes the controller 120 and the abnormality detector 122 of FIG. 1 by executing a program described later.

More specifically, the controller 120 has a target value with high responsiveness of the output of the power converter 62 by feedback using the output voltage of the power converter 62 and feed forward using the output of the input voltage monitor IC 70. The power converter 62 is controlled so as to be. However, the controller 120 is not limited to that, and based on the output of the input voltage monitor IC 70 and the output of the voltage adjustment circuit 74, at least the output system of the input voltage monitor IC 70 and the power converter 62 (secondary circuit of the transformer 80). In response to the occurrence of an abnormality in either one, a process of stopping the feed forward control for the power converter 62 is performed. However, even after the feed forward control is stopped, the controller 120 performs feedback control of the power converter 62 using the output of the voltage sensor 68.

As described above, in this embodiment, an abnormality has occurred in at least one of the input voltage monitor IC 70 and the output system of the power converter 62 based on the output of the input voltage monitor IC 70 and the output of the voltage adjustment circuit 74. In response to that, the feed forward control for the power converter 62 is stopped. It cannot be determined that an abnormality has occurred in the input voltage monitor IC 70, but at least when an abnormality has occurred in the input voltage monitor IC 70, it is detected and the feed forward control is stopped. As a result, it is possible to prevent the output of the power converter 62 from becoming unstable due to erroneous feed forward control. Further, even if the feedforward control is stopped, the feedback control is still executed. Therefore, although the response of the power converter 62 to the change of the input voltage is lowered, the operation can be continued almost as usual.

FIG. 3 shows the control structure of the program executed by the MCU 72 in a flowchart format. This program is repeatedly started at predetermined intervals necessary for controlling the power converter 62.

With reference to FIG. 3, this program determines whether or not the input voltage to the power converter 62 is within the normal range based on the input from the input voltage monitor IC 70, and the input voltage in step 230. Step 232, which branches the control flow depending on whether or not is determined to be normal, and when the determination in step 232 is negative, the processing when the input voltage value is abnormal is executed, and the execution of this program is terminated. Includes step 234 and. In step 234, for example, an appropriate process such as stopping the operation of the power converter 62 under the control of the controller 120 or displaying an error message and receiving an operator's instruction from an operation panel (not shown) may be performed. it can. Therefore, it is possible to prevent some problem from occurring by continuing the process as it is when the input voltage value is an abnormal value.

The program further comprises step 236, which calculates a control amount for feedback control of the half-bridge circuit 78 based on the output of the voltage sensor 68 shown in FIG. 1 in response to the affirmative determination in step 232. Following step 236, a step 238 for determining deterioration of the input voltage sensor (input voltage monitor IC 70) and a step 240 for branching the control flow according to the determination result in step 238 are included. In the determination in step 238, as will be described later, it cannot be determined whether the input voltage monitor IC 70 is deteriorated or the secondary circuit of the power converter 62 is abnormal. However, at least when the input voltage monitor IC 70 is deteriorated, it can be detected. In the following description, for the sake of brevity, determining whether or not an abnormality has occurred in at least one of the secondary side circuits of the input voltage monitor IC 70 and the power converter 62 is simply referred to as "input voltage sensor". Judging whether or not an abnormality has occurred in the

This program further controls the amount of control for feed-forward control of the half-bridge circuit 78 using the output of the input voltage monitor IC 70 in response to the determination in step 238 that no abnormality has occurred in the input voltage sensor. Step 242 to calculate, step 244 to correct the feedback control amount calculated in step 236 using the feed forward control amount calculated in step 242, and final control of the half bridge circuit 78 after the execution of step 246. It includes step 246, which determines the amount, outputs a signal for driving the MOSFETs 82 and 86, and ends the process.

When the determination in step 240 is affirmative, the processes of steps 242 and 244 are not executed, and step 246 is immediately executed. That is, when it is determined that the input voltage sensor is deteriorated, the feedforward control is not executed, and only the feedback control is executed. Since the feedback control is continued in this way, the power converter 62 does not stop, and the normal operation can be continued although the responsiveness is slightly lowered.

FIG. 4 shows the control structure of the routine executed in step 232 of FIG. 3 in the form of a flowchart. With reference to FIG. 4, this routine compares the input voltage V _IN _IC from the input voltage monitor IC 70 with the converted voltage V _IN _D output by the voltage regulator circuit 74 and sees if they match. Step 250 to branch the control flow according to the result, and a step to end the execution of this routine by setting a flag indicating that the input voltage sensor is deteriorated when the judgment of step 250 is negative. 252 and the like. If the determination in step 250 is affirmative, do nothing and end the execution of this routine. In step 240 of FIG. 3, it is determined whether or not the input voltage sensor has deteriorated and an abnormality has occurred by looking at the value of this flag. The flag indicating the deterioration of the input voltage sensor is reset before the process of step 250.

Values after converting the output voltage of the voltage sensor 104 becomes a value R _a of the formula (a1). If the simple relationship that the value calculated by the equation (a2) using this value matches the input voltage from the input voltage monitor IC 70 is established, the secondary circuit of the input voltage monitor IC 70 and the power converter 62 Are both considered normal. Otherwise, it means that an abnormality has occurred in either the input voltage monitor IC 70 or the secondary circuit of the power converter 62. The "match" in step 250 of FIG. 4 does not mean a perfect match. If the amount of difference between the two is within a certain range, it may be determined that they match. For example, if the absolute value of the difference between the two is within the threshold value, it may be determined to be normal, and if not, it may be determined to be abnormal. Therefore, the abnormality of the input voltage monitor IC 70 can be determined by using a simple index of the difference between the two. If the ratio of the latter value to the former value is within a predetermined range centered on 1, it may be determined that they match. Also in this case, the abnormality of the input voltage monitor IC 70 can be determined by using a simple index of the ratio of the two. In either case, this can be easily achieved using hardware and / or a combination of both.

In step 250, the value obtained by converting the voltage value obtained from the power converter 62 side is compared with the output value of the input voltage monitor IC 70. However, this embodiment is not limited to such a conversion method, and any conversion method can be used as long as it can be determined that a specific relationship having the same meaning as the above-mentioned relationship is established between the two. You may use it. For example, both may confirm that a specific relationship is established between the values converted separately. This conversion may be performed by hardware such as the voltage adjustment circuit 74 described above, or by software using the digitized data.

<motion>
The power conversion device 50 having the configuration described above operates as follows. First, it will be described in the order of normal, then when an abnormality occurs in the input voltage, and finally when the input voltage monitor IC 70 deteriorates.

-Normal-
With reference to FIG. 1, the voltage sensor 66 detects the input voltage to the power converter 62 and gives an analog signal to the input voltage monitor IC 70. The input voltage monitor IC 70 converts this value into a digital signal and gives it to the controller 120 and the abnormality detector 122. The voltage value output by the input voltage monitor IC 70 indicates a normal value. Therefore, the operation at the time of abnormality detection by the abnormality detector 122 is not performed. The voltage sensor 68 detects the output voltage of the power converter 62 and gives it to the controller 120 as an analog signal. This analog signal is digitized by an A / D converter (not shown) and given to the MCU 72 (control 120).

On the other hand, the analog signal output by the voltage sensor 104 is applied to the resistor 210 of the voltage dividing circuit 200 of the voltage adjusting circuit 74 shown in FIG. This voltage is divided and applied to the controller 120 via the filter 202 as shown by _Ra in FIG. This signal is converted into a digital signal by an A / D converter (not shown) and processed by the controller 120. The values of R ₁ and R ₂ are selected so that the voltage from the voltage sensor 104 matches the voltage represented by the output signal of the input voltage monitor IC 70 under normal conditions. That is, the signal output by the voltage adjustment circuit 74 is converted so that it can be compared whether or not the output of the voltage sensor 104 matches the input voltage monitor IC 70.

In the normal state, as described above, the voltage value represented by the input from the input voltage monitor IC 70 to the controller 120 and the voltage value represented by the output divided by the voltage adjusting circuit 74 are converted by the equation (a2). It matches the value that was set. As a result, the controller 120 corrects the control amount of the feedback control using the output of the voltage sensor 68 with the feedforward control amount using the input voltage value from the input voltage monitor IC 70, and outputs the drive signal of the half bridge circuit 78. it can.

In this case, the program shown in FIG. 3 is periodically executed by the MCU 72. First, in step 230, it is determined whether or not the input voltage value from the input voltage monitor IC 70 is within the normal range. In this example, the input voltage value is within the normal range, so the determination in step 232 is affirmative. Control proceeds to step 236. The determinations in steps 230 and 232 correspond to the functions of the anomaly detector 122 in FIG.

In step 236, the MCU 72 uses the output from the voltage sensor 68 to calculate the control amount for the feedback control of the half-bridge circuit 78. In the following step 238, it is determined whether or not the input voltage sensor (input voltage monitor IC70) has deteriorated. Specifically, with reference to FIG. 4, it is determined in step 250 whether or not the voltage value from the input voltage monitor IC 70 and the voltage value from the voltage adjustment circuit 74 match. Here, since both the input voltage monitor IC 70 and the secondary circuit of the power converter 62 are normal, the determination is affirmative, and the flag indicating the deterioration of the input voltage sensor is reset.

Returning to FIG. 3, the determination in step 240 is negative, and the processes of steps 242 and 244 are executed. That is, the feedforward control amount using the output of the input voltage monitor IC 70 is calculated (step 242), and the feedback control amount calculated in step 236 is corrected by the feedforward control amount calculated in step 242. Finally, in step 246, the control amount of the half-bridge circuit 78 is determined and output, and the execution of this program ends. The switching elements (MOSFETs 82 and 86) of the half-bridge circuit 78 are driven with a duty ratio according to the output control amount, and the power converter 62 converts the input voltage into a predetermined voltage and applies it to the load 64.

The MCU 72 appropriately operates the power converter 62 by executing a program showing the control structure in FIG. 3 at predetermined intervals.

-When the input voltage is abnormal-
When an abnormality occurs in the input voltage, the output of the input voltage monitor IC 70 deviates from the normal range. The abnormality detector 122 detects this and executes a predetermined process when the input voltage is abnormal.

Specifically, if the program shown in FIG. 3 is started after an abnormality occurs in the input voltage, the determination in step 232 in FIG. 3 is negative. In step 234, the process when the input voltage value is abnormal is executed. For example, the operation of the power converter 62 is stopped, and the program shown in FIG. 3 is not executed until the abnormality is resolved.

-Abnormality of input voltage monitor IC70-
When the voltage value output by the input voltage monitor IC 70 is within the normal range due to deterioration of the input voltage monitor IC 70, but it is not actually the correct value, or when an abnormality occurs in the secondary circuit of the power converter 62. When the program of FIG. 3 is started immediately after that, the determination of step 232 of FIG. 3 becomes affirmative, step 236 is executed, and the feedback control amount is calculated. However, when the voltage value output by the input voltage monitor IC 70 is not a correct value, a deviation occurs from the voltage value represented by the output of the voltage adjusting circuit 74 shown in FIG. As a result, the determination in step 250 shown in FIG. 4 is negative, and the determination in step 240 in FIG. 3 is negative. Control proceeds directly from step 240 to step 246 without performing the processes of steps 242 and 244. In step 246, the control amount for controlling the switching element of the half-bridge circuit 78 is determined and output by using the feedback control amount calculated in step 236 without being corrected by the feedforward control amount.

The switching elements (MOSFETs 82 and 86) of the half-bridge circuit 78 are driven with a duty ratio according to the output control amount, and the power converter 62 converts the input voltage into a predetermined voltage and applies it to the load 64. However, in this case, since the control amount is not corrected by the feed forward control amount, the response of the power converter 62 to the fluctuation of the input voltage is slightly delayed, unlike the normal state.

As described above, according to this embodiment, when some abnormality occurs in the secondary circuit of the input voltage monitor IC 70 or the power converter 62, the feed forward control is not performed. Therefore, the risk of causing a problem in the operation of the power converter 62 due to this abnormality can be reduced. Further, since the feedback control is continuously performed, the power converter 62 can be operated almost normally, although the response of the power converter 62 to the fluctuation of the input voltage is slightly slowed down.

As a result, if there is a possibility that some abnormality has occurred in the part that monitors the input voltage (or the secondary side circuit of the power converter 62), a power converter that can detect it and maintain almost normal operation can get.

In the above embodiment, the power converter 62 includes a half-bridge circuit 78 as a switching circuit. However, the switching circuit used in this embodiment is not limited to the half-bridge circuit. For example, even if a full bridge circuit is used, a power converter having the same function as that of this embodiment can be implemented.

[Embodiment 2]
<Constitution>
FIG. 5 shows a schematic configuration of the vehicle according to the second embodiment. With reference to FIG. 5, the vehicle 260 according to the second embodiment is a vehicle body 270 having a basic configuration as a vehicle such as wheels, and a high-voltage power source (for example, 48 to 300 V) provided in the vehicle body 270. It operates by the power supplied from the high-voltage battery 280 and the high-voltage battery 280 to provide the driving force of the vehicle body 270, or convert the kinetic energy lost by the vehicle 260 when the vehicle 260 is braked into electric current and supply it to the high-voltage battery 280. A generator / drive motor 282, a high-voltage operating unit 284 that operates with a high-voltage DC voltage supplied from the high-voltage battery 280, a low-voltage (for example, 12V) battery 288, and a low-voltage battery 288 supplied from the battery 288. It includes an auxiliary machine 290 operated by electric power and a DC (direct current) -DC converter 286 for stepping down the high-voltage direct current power supplied from the high-voltage battery 280 to, for example, 12V and supplying the battery 288 and the auxiliary machine 290 and the like. ..

As the DC-DC converter 286, the power conversion device 50 described as the first embodiment can be used.

<motion>
High-voltage power is stored in the high-voltage battery 280, and the generator / drive motor 282 uses this power to drive the vehicle 260. The high-voltage operating unit 284 also operates using the electric power from the high-voltage battery 280. On the other hand, the DC-DC converter 286 steps down the high voltage power from the high voltage battery 280 to, for example, 12V, and supplies the high voltage power to the battery 288 and the auxiliary machine 290. The battery 288 outputs power to the auxiliary machine 290 when the power consumption of the auxiliary machine 290 is large. When the power consumption of the auxiliary machine 290 is small, the battery 288 stores the power supplied from the DC-DC converter 286.

Since the DC-DC converter 286 is the same as the power conversion device 50 according to the first embodiment, it normally operates with high responsiveness by the feed forward control and the feedback control as in the first embodiment, and when an abnormality occurs in the input voltage, it operates. Appropriate measures can be taken, and even when some abnormality occurs in the input voltage monitor circuit, stable operation can be performed to some extent only by feedback control.

[Realization by dedicated computer]
In the power conversion device 50 according to the first embodiment and the DC-DC converter 286 of the second embodiment, the MCU 72 is realized by a dedicated computer programmed by a program showing a control structure in FIGS. 3 and 4. The hardware configuration of the MCU 72 is shown in FIG.

With reference to FIG. 6, the MCU 72 is a drive signal that generates a drive signal of the half bridge circuit 78 according to various sensors 402 such as an input voltage monitor IC 70, a voltage sensor 104, and a voltage sensor 66, and a control signal output from the MCU 72. Includes a dedicated computer 400 connected to the generation circuit 404 and programmed by the programs shown in FIGS. 3 and 4 to output control signals to the drive signal generation circuit 404 according to outputs from various sensors 402.

The dedicated computer 400 is connected to the CPU (Central Processing Unit) 450 and the CPU 450, and is connected to the bus 452 and the bus 452 that provide the data and control signal paths between the CPU 450 and each part of the MCU 72 to the CPU 450, and is executed by the CPU 450. A ROM (Read-Only Memory) 454 that stores various programs such as a start-up program, a RAM 456 that is connected to the bus 452 and stores programs and data executed by the CPU 450, and a program that is connected to the bus 452 and is connected to the CPU 450. And a rewritable and non-volatile auxiliary storage 458 for storing data and the like necessary for its execution.

The dedicated computer 400 is further connected to the bus 452 and stores the inputs from the various sensors 402 at the predetermined addresses of the RAM 456 via the bus 452, or reads the control signal output by the CPU 450 and stored in the RAM 456 to generate a drive signal. It includes an input / output interface (I / F) 460 for giving to the 404.

The program whose control structure is shown in FIGS. 3 and 4 is stored in, for example, ROM 454, and is loaded into RAM 456 at the time of execution. The CPU 450 reads and interprets an instruction from an address specified by a program counter (not shown) in the RAM 456, and specifies it by an instruction in a register (ROM 454, RAM 456, and an input / output I / F 460) in the CPU 450. The data is read from the specified address and the instruction is executed. The CPU 450 stores the result of executing the instruction at the address also specified by the instruction. By executing the program in this way, the CPU 450 realizes the controller 120 and the abnormality detector 122 shown in FIG. The computer programs of these plurality of devices can be installed from an external server device or the like. Further, the computer programs of these plurality of devices are distributed in a state of being stored in a recording medium such as a CD (Compact Disc) -ROM, a DVD (Digital Versatile disc) -ROM, or a semiconductor memory, respectively.

[Modification example]
In the above embodiment, the voltage adjustment circuit 74 is used to convert the output of the voltage sensor 104, and the result is compared with the output of the input voltage monitor IC 70 by software. However, this disclosure is not limited to such embodiments. _Ra can be calculated from the conversion formula of the formula (a2) representing the normal time. Therefore, the voltage sensor 104 is digitized as it is, and the output of the voltage sensor 104 is converted by substituting it into the V of the equation (a2) in the MCU 72 to obtain the theoretical _VIN, and the obtained V _IN value and the input voltage. The output of the monitor IC 70 may be compared in step 250 of FIG.

Alternatively, the output of the input voltage monitor IC70 is used as an analog signal, the difference from the output by the voltage adjustment circuit 74 shown in FIG. 1 is obtained by a circuit, and the signal is thresholded by two comparators corresponding to the upper limit and the lower limit of the normal range. The functions of steps 250 and 252 of FIG. 4 may be realized by comparing with the values.

It should be considered that the embodiments disclosed this time are exemplary in all respects and not restrictive. The scope of this disclosure is not indicated by the description of the detailed description of the invention, but is indicated by each claim of the claims, and all modifications within the meaning and scope equivalent to the wording of the claims. Is intended to be included.

50 Power converter 60 DC power supply 62 Power converter 64 Load 66, 68, 104 Voltage sensor 70 Input voltage monitor IC
72 MCU
74 Voltage adjustment circuit 78 Half bridge circuit 80 Transformer 82, 86 MOSFET
84, 88 Body diode 90, 92, 94, 102 Capacitor 96, 98 Diode 100 Reactor 120 Controller 122 Abnormality detector 200 Voltage divider 202 Filter 210, 212 Resistor 230, 232, 234, 236, 238, 240, 242, 244, 246, 250, 252 Step 260 Vehicle 270 Body 280 High-voltage battery 282 Generator / drive motor 284 High-voltage operating unit 286 DC-DC converter 288 Battery 290 Auxiliary machine 400 Dedicated computer 402 Various sensors 404 Drive signal generation circuit 450 CPU
452 Bus 454 ROM
456 RAM
458 Auxiliary storage 460 I / O I / F

Claims (10)

Power converter and
An input voltage monitor circuit that monitors the input voltage to the power converter,
A control circuit that responds to the output voltage of the power converter and the output of the input voltage monitor circuit and controls the power converter so that the output of the power converter becomes a target value.
Based on the output of the input voltage monitor circuit and the voltage at a predetermined position in the power converter, it is determined whether or not an abnormality has occurred in either the output system of the power converter or the input voltage monitor circuit. A power conversion device including an abnormality determination circuit that adjusts control of the power converter by the control circuit according to a determination result. The abnormality determination circuit is
It is determined whether or not an abnormality has occurred in either the output system or the input voltage monitor circuit depending on whether or not a predetermined relationship is established between the output of the input voltage monitor circuit and the voltage at the predetermined position. Judgment circuit to
The power conversion device according to claim 1, further comprising an adjustment circuit that adjusts control of the power converter by the control circuit according to a determination result of the determination circuit. The control circuit performs feed-forward control of the power converter using the output of the input voltage monitor circuit.
The power conversion device according to claim 2, wherein the adjustment circuit stops the feed forward control by the control circuit in response to the determination that an abnormality has occurred by the abnormality determination circuit. The determination circuit
The output of the input voltage monitor circuit and the output of the input voltage monitor circuit when the input voltage monitor circuit and the power converter are operating normally between the output of the input voltage monitor circuit and the voltage at the predetermined position. A conversion circuit that converts at least one of the output of the input voltage monitor circuit and the voltage at the predetermined position according to a predetermined conversion formula so that the converted values with the voltage at the predetermined position are equal.
An abnormality occurred in either the output system or the input voltage monitor circuit depending on whether or not the output of the input voltage monitor circuit and the voltage at the predetermined position match after at least one of them has been converted by the conversion circuit. The power conversion device according to claim 2 or 3, further comprising a conversion value comparison circuit for determining whether or not. The power converter
A switching circuit including a plurality of switching elements that receive the input voltage as an input and perform switching according to the control of the control circuit.
A transformer with a primary coil connected to the output of the switching circuit,
Including a rectifier circuit connected to the secondary coil of the transformer
The rectifier circuit includes a diode for rectifying the output voltage of the transformer.
The power conversion device according to any one of claims 1 to 4, wherein the predetermined position is a voltage on the cathode side of the diode. The conversion circuit
A _first resistor having a resistance value of R1 having one terminal connected to the predetermined position and the other terminal connected to the input of the conversion value comparison circuit.
A _second resistor having a resistance value of R2, which is connected between the other terminal of the first resistor and the reference voltage, is included.
The voltage division ratio at the other terminal by the first resistor and the second resistor is calculated by the following equation (1).

The conversion circuit further includes a calculation circuit for calculating an input voltage V _IN to be compared with the output of the input voltage monitor circuit from the voltage V on the cathode side of the diode according to the following equation (2). The power converter described.

However, N = the turns ratio of the transformer,
duty = duty ratio of the switching element of the switching circuit,
Vf = forward voltage of the diode,
1000 represents the unit conversion coefficient from volt to millivolt, respectively. When the absolute value of the difference between the value _VIN calculated by the equation (2) and the output of the input voltage monitor circuit is equal to or greater than a predetermined positive threshold value, the converted value comparison circuit has the output system and The power conversion device according to claim 6, wherein it is determined that an abnormality has occurred in any of the input voltage monitor circuits. In the conversion value comparison circuit, the ratio of the value of the value _VIN calculated by the equation (2) to the output of the input voltage monitor circuit is greater than or equal to the first threshold value greater than 1, or less than the second threshold value. The power conversion device according to claim 6, wherein it is determined that an abnormality has occurred in either the output system or the input voltage monitor circuit when the value is equal to or lower than the threshold value. With the car body
A battery provided in the vehicle body that stores and outputs electric power at the first voltage,
A low-voltage operating unit provided on the vehicle body and operating at a second voltage lower than the first voltage.
The invention according to any one of claims 1 to 8, wherein the vehicle body receives the output of the battery as an input, converts it into the second voltage, and supplies the output to the low voltage operating unit. Vehicles, including power converters. One of a power converter, an input voltage monitor circuit for monitoring the input voltage to the power converter, a control circuit for controlling the power converter, an output system of the power converter, and an input voltage monitor circuit. An operation method of a power converter including an abnormality determination circuit for determining whether or not an abnormality has occurred.
A step in which the input voltage monitor circuit monitors the input voltage to the power converter and outputs a signal representing the input voltage.
A step in which the control circuit responds to the signal output by the input voltage monitor circuit and the output voltage of the power converter, and controls the power converter so that the output of the power converter becomes a target value. When,
Whether the abnormality determination circuit has caused an abnormality in either the output system or the input voltage monitor circuit based on the signal output by the input voltage monitor circuit and the voltage at a predetermined position in the power converter. A method of operating a power converter, which includes a step of determining whether or not to use the power converter and adjusting the control of the power converter by the control circuit according to the determination result.

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