JP5780197B2 - Voltage converter - Google Patents

Description

  The present invention relates to a technical field of a voltage conversion device mounted on, for example, a vehicle.

  2. Description of the Related Art In recent years, as an environmentally-friendly vehicle, an electric vehicle that is mounted with a power storage device (for example, a secondary battery or a capacitor) and travels using a driving force generated from electric power stored in the power storage device has attracted attention. Examples of the electric vehicle include an electric vehicle, a hybrid vehicle, and a fuel cell vehicle.

  In these electric vehicles, a motor generator for generating driving force for traveling by receiving electric power from the power storage device when starting or accelerating, and generating electric power by regenerative braking during braking to store electric energy in the power storage device May be provided. Thus, in order to control a motor generator according to a driving | running | working state, an inverter is mounted in an electric vehicle.

  In such a vehicle, a voltage conversion device (converter) may be provided between the power storage device and the inverter in order to stably supply power used by the inverter that varies depending on the vehicle state. With this converter, the inverter input voltage can be made higher than the output voltage of the power storage device to increase the output of the motor and reduce the motor current at the same output, thereby reducing the size and cost of the inverter and motor. Can be achieved.

  The converter is provided with sensors that detect the input voltage (ie, the voltage before conversion) and the output voltage (ie, the voltage after conversion), and the current flowing through the reactor, and according to the parameters detected by these sensors. The operation of the converter is controlled. For example, Patent Document 1 proposes a technique for generating a gate drive signal using an input voltage, an output voltage, and a reactor current.

JP 2007-221920 A

  However, when a relatively large number of sensors are provided in the converter as in the technique described in Patent Document 1 described above, for example, the manufacturing cost increases as the number of sensors increases. Moreover, since it is required to handle many signals output from each sensor, the system configuration is also complicated. Therefore, the voltage converter described in Patent Document 1 described above can achieve suitable control based on the input voltage and output voltage, and the reactor current, but has various disadvantages due to the increase in the number of sensors. There is a technical problem that occurs.

  The present invention has been made in view of the above-described problems, and an object thereof is to provide a voltage conversion device capable of detecting an input voltage and an output voltage with a relatively simple configuration.

In order to solve the above-described problem, a voltage converter according to the present invention is configured to include a reactor, a first switching element and a second switching element connected in series to the reactor, and a current detection unit that detects a reactor current flowing through the reactor. Change rate calculation means for calculating a change rate of the reactor current, an input voltage input to the first switching element and the second switching element using the change rate of the reactor current and the inductance of the reactor, And voltage estimation means for estimating one of the output voltages output from the first switching element and the second switching element , and the current detection means includes the first switching element and the first switching element. 2 Carrier signal peak that defines the switching timing of each switching element The reactor current is detected a plurality of times at a timing of a first predetermined range including the change rate calculating means, and the rate of change of the reactor current is calculated from a plurality of values detected at a timing of the first predetermined range, The voltage estimation means estimates the input voltage using the rate of change of the reactor current and the inductance of the reactor .

  The voltage conversion device according to the present invention is a converter mounted on a vehicle, for example, and includes a first switching element and a second switching element that are respectively connected in series to a reactor. As the first switching element and the second switching element, for example, an IGBT (Insulated Gate Bipolar Transistor), a power MOS (Metal Oxide Semiconductor) transistor, or a power bipolar transistor can be used.

  For example, a diode is connected in parallel to each of the first switching element and the second switching element to form a first arm and a second arm, respectively. In other words, the first switching element forms a first arm, and the switching operation of the first arm can be switched on and off. Similarly, the second switching element forms a second arm, and on / off of driving in the second arm can be switched by the switching operation.

  When the voltage converter according to the present invention operates, for example, gate signals for switching on and off of each of the first switching element and the second switching element are generated. Specifically, for example, a duty command signal corresponding to the duty ratio of the first switching element and the second switching element and a carrier signal corresponding to the switching frequency of the first switching element and the second switching element are compared with each other. A gate signal is generated. The generated gate signal is supplied to the first switching element and the second switching element, whereby the driving of the first arm and the second arm of the voltage conversion device is controlled.

  Here, for the control of the voltage converter (specifically, for example, generation of the duty command signal described above), the reactor current flowing through the reactor, the input voltage of the voltage converter (that is, the voltage before conversion), and the output voltage Various parameters such as (ie, voltage after conversion) are used. These parameters can be detected by providing a dedicated sensor or the like, respectively, but if the number of sensors increases, there is a risk that the cost increases and the system becomes complicated. On the other hand, in the voltage converter according to the present invention, as described later, one of the input voltage and the output voltage is estimated without providing a dedicated sensor.

  In the voltage conversion device according to the present invention, when estimating the input voltage or the output voltage, first, the reactor current flowing through the reactor is detected by the current detection means. The current detection means is configured as a current sensor, for example. The current sensor is preferably capable of detecting a current at a high speed in order to calculate an instantaneous current change rate.

  When the reactor current is detected, the change rate of the reactor current is calculated by the change rate calculation means. The change rate of the reactor current is obtained, for example, by detecting the reactor current at a plurality of different timings and calculating the difference between the detected reactor currents.

  When the change rate of the reactor current is calculated, the input voltage or the output voltage of the voltage converter is estimated from the change rate of the reactor current and the known inductance of the reactor by the voltage estimation means. The input voltage can be estimated only from the reactor current change rate and the reactor inductance described above, but the output voltage is estimated using the input voltage in addition to the reactor current change rate and the reactor inductance. .

  As described above, according to the voltage converter of the present invention, the input voltage or the output voltage can be estimated without providing a dedicated voltage sensor. Therefore, it is possible to prevent the increase in cost and the complexity of the system due to the increase in the number of voltage sensors.

  In one aspect of the voltage conversion apparatus according to the present invention, the current detection means has a timing within a first predetermined range including a peak of a carrier signal that defines a switching timing of each of the first switching element and the second switching element. The reactor current is detected a plurality of times, the change rate calculating means calculates a change rate of the reactor current from a plurality of values detected at the timing of the first predetermined range, and the voltage estimating means is configured to detect the reactor current. The input voltage is estimated using the rate of change of the current and the inductance of the reactor.

  According to this aspect, in the current detection means, the reactor current is detected a plurality of times at the timing of the first predetermined range including the peak of the carrier signal. Here, the “first predetermined range” is set as an appropriate period for calculating the rate of change of the reactor current, and is a relatively short period (more specifically, at least the first switching element). And a period in which the peak and valley of the reactor current that rises and falls periodically according to the switching of the second switching element are not straddled).

  The carrier signal is a signal used for generating a gate signal for switching each of the first switching element and the second switching element. Specifically, the gate signal is generated by comparing the carrier signal and the duty command signal. For this reason, the peak of the carrier signal corresponds approximately to the midpoint of the rising period of the reactor current (that is, between the valley of the reactor current and the mountain). Therefore, if the reactor current is detected a plurality of times in the first predetermined range including the peak of the carrier signal, the change rate calculating means can suitably calculate the change rate (more accurately, the rate of increase) of the reactor current. In other words, it is possible to prevent the calculated change rate of the reactor current from becoming an inappropriate value by detecting the reactor current at a timing that crosses the peaks and valleys of the reactor current.

  If the rate of increase of the reactor is calculated as described above, the voltage estimation means can accurately estimate the input voltage from the rate of change of the reactor current and the inductance of the reactor. That is, it is possible to know the value of the input voltage without providing a sensor dedicated to the input voltage.

  In another aspect of the voltage conversion apparatus according to the present invention, an input voltage detection unit that detects the input voltage is provided, and the current detection unit defines a switching timing of each of the first switching element and the second switching element. The reactor current is detected a plurality of times at a timing of a second predetermined range including a trough of the carrier signal to be changed, and the change rate calculating means changes the reactor current from a plurality of values detected at the timing of the second predetermined range. The voltage estimation means estimates the output voltage using the change rate of the reactor current, the inductance of the reactor, and the input voltage.

  According to this aspect, the input voltage is detected by the input voltage detecting means. For this reason, the current estimation means estimates the remaining output voltage.

  In this aspect, in particular, the current detection means detects the reactor current a plurality of times at the timing of the first predetermined range including the valley of the carrier signal. The “second predetermined range” here is set as an appropriate period for calculating the rate of change of the reactor current, and is a relatively short period (more specifically, at least the first switching element). And a period in which the peak and valley of the reactor current that rises and falls periodically according to the switching of the second switching element are not straddled).

  The carrier signal is a signal used for generating a gate signal for switching each of the first switching element and the second switching element. Specifically, the gate signal is generated by comparing the carrier signal and the duty command signal. For this reason, the valley of the carrier signal corresponds to a substantially middle point in the falling period of the reactor current (that is, between the peak and valley of the reactor current). Therefore, if the reactor current is detected a plurality of times within the second predetermined range including the valley of the carrier signal, the change rate calculating means can suitably calculate the reactor current change rate (precisely, the decrease rate). In other words, it is possible to prevent the calculated change rate of the reactor current from becoming an inappropriate value by detecting the reactor current at a timing that crosses the peaks and valleys of the reactor current.

  As described above, if the descending rate of the reactor is calculated, the voltage estimation means can accurately estimate the output voltage from the rate of change of the reactor current, the inductance of the reactor, and the input voltage. In other words, the value of the output voltage can be known without providing a sensor dedicated to the output voltage.

  If the output voltage detection means is provided instead of the input voltage detection means (that is, if the output voltage can be detected instead of the input voltage), the input voltage can be estimated by the power estimation means. . In other words, the input voltage can be estimated from the change rate of the reactor current calculated as described above, the inductance of the reactor, and the output voltage.

  The effect | action and other gain of this invention are clarified from the form for implementing invention demonstrated below.

1 is a schematic diagram illustrating an overall configuration of a vehicle in which a voltage conversion device according to a first embodiment is mounted. It is a block diagram which shows the structure of ECU which concerns on 1st Embodiment. It is a circuit diagram which shows the structure of an input voltage estimation circuit. 6 is a timing chart showing sampling timing of IL according to the first embodiment. It is the schematic which shows the whole structure of the vehicle by which the voltage converter which concerns on 2nd Embodiment is mounted. It is a block diagram which shows the structure of ECU which concerns on 2nd Embodiment. It is a circuit diagram which shows the structure of an output voltage estimation circuit. It is a timing chart which shows the sampling timing of IL which concerns on 2nd Embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<First Embodiment>
First, the overall configuration of a vehicle on which the voltage conversion device according to the first embodiment is mounted will be described with reference to FIG. FIG. 1 is a schematic diagram showing the overall configuration of a vehicle on which the voltage conversion device according to the first embodiment is mounted.

  In FIG. 1, a vehicle 100 on which the voltage conversion device according to the present embodiment is mounted is configured as a hybrid vehicle using an engine 40 and motor generators MG1 and MG2 as power sources. However, the configuration of the vehicle 100 is not limited to this, and the vehicle 100 can be applied to a vehicle (for example, an electric vehicle or a fuel cell vehicle) that can be driven by electric power from the power storage device.

  Moreover, although this embodiment demonstrates the structure by which a voltage converter is mounted in the vehicle 100, if it is an apparatus driven by an alternating current motor other than a vehicle, it is applicable.

  The vehicle 100 includes a DC voltage generator 20, a load device 45, a smoothing capacitor C2, and an ECU 30.

  DC voltage generation unit 20 includes a power storage device 28, system relays SR1 and SR2, a smoothing capacitor C1, and a converter 12.

  The power storage device 28 includes a secondary battery such as nickel hydride or lithium ion, and a power storage device such as an electric double layer capacitor.

  System relay SR1 is connected between the positive terminal of power storage device 28 and power line PL1, and system relay SR2 is connected between the negative terminal of power storage device 28 and ground line NL. System relays SR <b> 1 and SR <b> 2 are controlled by a signal SE from ECU 30, and switch between supply and interruption of power from power storage device 28 to converter 12.

  Converter 12 is an example of the “voltage converter” of the present invention, and includes a reactor L1, switching elements Q1 and Q2, and diodes D1 and D2.

  The switching elements Q1 and Q2 are examples of the “first switching element” and the “second switching element” of the present invention, and are connected in series between the power line PL2 and the ground line NL. Switching elements Q1 and Q2 are controlled by a switching control signal PWC from ECU 30.

  As the switching elements Q1 and Q2, for example, an IGBT, a power MOS transistor, a power bipolar transistor, or the like can be used. Anti-parallel diodes D1 and D2 are arranged for switching elements Q1 and Q2.

  Reactor L1 is provided between a connection node of switching elements Q1 and Q2 and power line PL1. Smoothing capacitor C2 is connected between power line PL2 and ground line NL. Reactor current IL that is a current flowing through the reactor is detected by current sensor 18 and output to ECU 30. The current sensor 18 here is an example of the “current detection means” in the present invention.

  Load device 45 includes an inverter 23, motor generators MG <b> 1 and MG <b> 2, an engine 40, a power split mechanism 41, and drive wheels 42. Inverter 23 includes an inverter 14 for driving motor generator MG1 and an inverter 22 for driving motor generator MG2. As shown in FIG. 1, it is not essential to provide two sets of inverters and motor generators. For example, only one set of inverter 14 and motor generator MG1 or inverter 22 and motor generator MG2 may be provided.

  Motor generators MG1 and MG2 receive AC power supplied from inverter 23 and generate rotational driving force for vehicle propulsion. Motor generators MG1 and MG2 receive rotational force from the outside, generate AC power according to a regenerative torque command from ECU 30, and generate regenerative braking force in vehicle 100.

  Motor generators MG1 and MG2 are also coupled to engine 40 via power split mechanism 41. Then, the driving force generated by engine 40 and the driving force generated by motor generators MG1, MG2 are controlled to have an optimal ratio. Alternatively, either one of motor generators MG1 and MG2 may function exclusively as an electric motor, and the other motor generator may function exclusively as a generator. In the present embodiment, it is assumed that motor generator MG1 functions as a generator driven by engine 40, and motor generator MG2 functions as an electric motor that drives drive wheels 42.

  For the power split mechanism 41, for example, a planetary gear mechanism (planetary gear) is used in order to distribute the power of the engine 40 to both the drive wheels 42 and the motor generator MG1.

  Inverter 14 receives the boosted voltage from converter 12, and drives motor generator MG1 to start engine 40, for example. Inverter 14 also outputs regenerative power generated by motor generator MG <b> 1 by mechanical power transmitted from engine 40 to converter 12. At this time, converter 12 is controlled by ECU 30 to operate as a step-down circuit.

  Inverter 14 is provided in parallel between power line PL2 and ground line NL, and includes U-phase upper and lower arms 15, V-phase upper and lower arms 16, and W-phase upper and lower arms 17. Each phase upper and lower arm is composed of a switching element connected in series between power line PL2 and ground line NL. For example, the U-phase upper and lower arms 15 are composed of switching elements Q3 and Q4, the V-phase upper and lower arms 16 are composed of switching elements Q5 and Q6, and the W-phase upper and lower arms 17 are composed of switching elements Q7 and Q8. Antiparallel diodes D3 to D8 are connected to switching elements Q3 to Q8, respectively. Switching elements Q3 to Q8 are controlled by a switching control signal PWI from ECU 30.

  For example, motor generator MG1 is a three-phase permanent magnet type synchronous motor, and one end of three coils of U, V, and W phases is commonly connected to a neutral point. Further, the other end of each phase coil is connected to a connection node of switching elements of upper and lower arms 15 to 17 for each phase.

  Inverter 22 is connected to converter 12 in parallel with inverter 14.

  Inverter 22 converts the DC voltage output from converter 12 into three-phase AC and outputs the same to motor generator MG2 that drives drive wheels. Inverter 22 also outputs regenerative power generated by motor generator MG2 to converter 12 along with regenerative braking. At this time, converter 12 is controlled by ECU 30 to operate as a step-down circuit. Although the internal configuration of the inverter 22 is not shown, it is the same as that of the inverter 14 and will not be described in detail.

  Converter 12 is basically controlled such that switching elements Q1 and Q2 are turned on and off in a complementary manner in each switching period. During the boosting operation, converter 12 boosts DC voltage VL supplied from power storage device 28 to DC voltage VH (this DC voltage corresponding to the input voltage to inverter 14 is also referred to as “system voltage” hereinafter). This boosting operation is performed by supplying the electromagnetic energy accumulated in the reactor L1 during the ON period of the switching element Q2 to the power line PL2 via the switching element Q1 and the antiparallel diode D1.

  In the present embodiment, in particular, the boosted DC voltage VH is detected by the voltage sensor 13 and output to the ECU 30. On the other hand, no voltage sensor corresponding to the DC voltage VL before boosting is provided. The DC voltage VL is estimated by using the reactor current IL or the like in the ECU 30 as will be described later. Incidentally, the direct current VL is an example of the “input voltage” in the present embodiment, and the direct current voltage VH is an example of the “output voltage” in the present invention. Hereinafter, the DC voltage VL may be referred to as an input voltage VL, and the DC voltage VH may be referred to as an output voltage VH.

  Converter 12 steps down DC voltage VH to DC voltage VL during the step-down operation. This step-down operation is performed by supplying the electromagnetic energy accumulated in the reactor L1 during the ON period of the switching element Q1 to the ground line NL via the switching element Q2 and the antiparallel diode D2.

  The voltage conversion ratio (the ratio of VH and VL) in these step-up and step-down operations is controlled by the on-period ratio (duty ratio) of the switching elements Q1 and Q2 in the switching period. If switching elements Q1 and Q2 are fixed to ON and OFF, respectively, VH = VL (voltage conversion ratio = 1.0) can be obtained.

  Smoothing capacitor C <b> 2 smoothes the DC voltage from converter 12 and supplies the smoothed DC voltage to inverter 23. The voltage sensor 13 detects the voltage across the smoothing capacitor C2, that is, the output voltage VH, which is a system voltage, and outputs the detected value to the ECU 30.

  When the torque command value of motor generator MG1 is positive (TR1> 0), inverter 14 responds to switching control signal PWI1 from ECU 30 when a DC voltage is supplied from smoothing capacitor C2, and switching elements Q3-Q8 The motor generator MG1 is driven so as to convert a DC voltage into an AC voltage and output a positive torque by the switching operation. Further, when the torque command value of motor generator MG1 is zero (TR1 = 0), inverter 14 converts the DC voltage into the AC voltage and the torque becomes zero by the switching operation in response to switching control signal PWI1. In this manner, motor generator MG1 is driven. Thus, motor generator MG1 is driven to generate zero or positive torque designated by torque command value TR1.

  Furthermore, during regenerative braking of vehicle 100, torque command value TR1 of motor generator MG1 is set negative (TR1 <0). In this case, inverter 14 converts the AC voltage generated by motor generator MG1 into a DC voltage by a switching operation in response to switching control signal PWI1, and converts the converted DC voltage (system voltage) to smoothing capacitor C2. To the converter 12. The regenerative braking here refers to braking with regenerative power generation when the driver operating the electric vehicle performs a footbrake operation, or regenerative braking by turning off the accelerator pedal while driving, although the footbrake is not operated. This includes decelerating (or stopping acceleration) the vehicle while generating electricity.

  Similarly, inverter 22 receives switching control signal PWI2 from ECU 30 corresponding to the torque command value of motor generator MG2, receives a switching control signal PWI2, and converts the DC voltage into an AC voltage to a predetermined torque by a switching operation. The motor generator MG2 is driven so that

  Current sensors 24 and 25 detect motor currents MCRT1 and MCRT2 flowing through motor generators MG1 and MG2, and output the detected motor currents to ECU 30. Since the sum of the instantaneous values of the currents of the U-phase, V-phase, and W-phase is zero, the current sensors 24 and 25 are arranged to detect the motor current for two phases as shown in FIG. All you need is enough.

  Rotation angle sensors (resolvers) 26 and 27 detect rotation angles θ1 and θ2 of motor generators MG1 and MG2, and send the detected rotation angles θ1 and θ2 to ECU 30. ECU 30 can calculate rotational speeds MRN1, MRN2 and angular speeds ω1, ω2 (rad / s) of motor generators MG1, MG2 based on rotational angles θ1, θ2. Note that the rotation angle sensors 26 and 27 may not be arranged by directly calculating the rotation angles θ1 and θ2 from the motor voltage and current in the ECU 30.

  ECU 30 includes a CPU (Central Processing Unit), a storage device, and an input / output buffer, and controls each device of vehicle 100. Note that the control performed by the ECU 30 is not limited to processing by software, and can be constructed and processed by dedicated hardware (electronic circuit).

  As a representative function, the ECU 30 receives the input torque command values TR1 and TR2, the system voltage VH detected by the voltage sensor 13 and the motor currents MCRT1 and MCRT2 from the current sensors 24 and 25, and the rotation angle sensors 26 and 27. Are controlled so that motor generators MG1 and MG2 output torques according to torque command values TR1 and TR2. That is, switching control signals PWC, PWI1, and PWI2 for controlling converter 12 and inverter 23 as described above are generated and output to converter 12 and inverter 23, respectively.

  During the boost operation of converter 12, ECU 30 feedback-controls system voltage VH, and generates switching control signal PWC so that system voltage VH matches the voltage command value.

  Further, when vehicle 100 enters the regenerative braking mode, ECU 30 generates switching control signals PWI1 and PWI2 so as to convert the AC voltage generated by motor generators MG1 and MG2 into a DC voltage, and outputs it to inverter 23. Thus, inverter 23 converts the AC voltage generated by motor generators MG1 and MG2 into a DC voltage and supplies it to converter 12.

  Further, when vehicle 100 enters the regenerative braking mode, ECU 30 generates a switching control signal PWC so as to step down the DC voltage supplied from inverter 23 and outputs it to converter 12. Thus, the AC voltage generated by motor generators MG1 and MG2 is converted into a DC voltage, and is further stepped down and supplied to power storage device 28.

  Here, a specific configuration of the above-described ECU will be described with reference to FIG. FIG. 2 is a block diagram showing the configuration of the ECU according to the first embodiment. In FIG. 2, for convenience of explanation, only the parts deeply related to the present embodiment are shown among the parts provided in the ECU 30, and other detailed parts are appropriately omitted.

  2, the ECU 30 includes an input voltage estimation circuit 310, a voltage control unit 320, a current control unit 330, a gate signal output circuit 340, and a carrier signal output unit 350.

  The input voltage estimation circuit 310 estimates the input voltage VL before boosting based on the input reactor current IL (that is, the current value detected by the current sensor 18) and the inductance value of the reactor L1 stored in advance. To do. The estimated input voltage VL is output to the voltage controller 320.

  The voltage control unit 320 calculates a voltage deviation based on the output voltage VH (that is, the boosted voltage value detected by the voltage sensor 13) and the input voltage VL estimated by the input voltage estimation circuit 310, and the reactor current The command value ILREF is calculated. The calculated reactor current command value ILREF is output to the current control unit 330.

  Current control unit 330 calculates a current deviation based on reactor current command value ILREF input from voltage control unit 320 and detected reactor current IL, and calculates duty command signal DUTY for switching elements Q1 and Q2. . The calculated duty command signal DUTY is output to the gate signal output circuit 340.

  Based on the duty command signal DUTY input from the current control unit 330 and the carrier signal CR generated in the carrier signal generation unit 350, the gate signal output circuit 340 includes PWC1 and PWC1 which are gate signals of the switching elements Q1 and Q2. PWC2 is generated.

  The carrier signal generation unit 350 generates a carrier signal CR having a predetermined period in order to generate the switching control signals PWC1 and PWC2. The carrier signal CR is output to the gate signal output circuit 350. The carrier signal CR is also output to the input voltage estimation circuit 310.

  The ECU 30 described above is an integrated electronic control unit configured to include the above-described parts, and all the operations related to the parts are configured to be executed by the ECU 30. However, the physical, mechanical, and electrical configurations of the above-described parts according to the present invention are not limited thereto. For example, each of these means includes various ECUs, various processing units, various controllers, microcomputer devices, and the like. It may be configured as a computer system or the like.

  Next, a specific configuration of the input voltage estimation circuit 310 included in the ECU 30 will be described with reference to FIG. FIG. 3 is a circuit diagram showing the configuration of the input voltage estimation circuit.

  In FIG. 3, the input voltage estimation circuit 310 includes an ADC (Analog to Digital Converter) 311, a sampling timing generation circuit 312, a current change rate calculation unit 313, and an input voltage calculation unit 314.

  The ADC 311 samples the value of the reactor current IL at a plurality of different timings and outputs it to the current change rate calculation unit 313. The ADC 311 samples the reactor current IL at a timing based on the timing signal input from the sampling timing generation circuit 312.

  Sampling timing generation circuit 312 generates a timing signal indicating the sampling timing of reactor current IL based on carrier signal CR. Specifically, the sampling timing generation circuit 312 generates a timing signal so that the sampling timing is within a predetermined range including a peak of the carrier signal CR.

  The current change rate calculation unit 313 is an example of the “change rate calculation unit” of the present invention, and the time rate of change of the reactor current IL (in other words, the reactor current IL from the values of the reactor current IL sampled at a plurality of timings in the ADC 311). A time differential value dIL / dT of the current IL is calculated. A method for calculating the time change rate of the reactor current IL will be described in detail later.

  The input voltage calculation unit 314 is an example of the “voltage estimation unit” of the present invention, and calculates (estimates) the input voltage VL using the time change rate of the reactor current IL calculated by the current change rate calculation unit 313. . The input voltage calculation unit 314 stores the inductance value of the reactor L1 in advance.

  As described above, the input voltage estimation circuit 310 estimates the input voltage VL by performing various calculations after sampling the reactor current L1 at a timing based on the carrier signal CR.

  Next, a specific operation when the input voltage estimation circuit 310 estimates the input voltage VL will be described with reference to FIG. 4 in addition to FIG. FIG. 4 is a timing chart showing IL sampling timing according to the first embodiment.

  In FIG. 4, it is assumed that the carrier signal CR is generated as a signal having a period as shown in the figure, and the duty command signal DUTY is constant at about 50%.

  In this case, the gate signal PWC1 of the switching element Q1 is changed from the Hi level (that is, the level corresponding to the ON state of the switching element Q1) to the Lo level (that is, the switching element Q1) at the timing when the rising carrier signal CR overlaps the duty command signal DUTY. Level corresponding to off). On the other hand, the gate signal PWC2 of the switching element Q2 changes from the Hi level to the Lo level at the timing when the falling carrier signal CR overlaps the duty command signal DUTY.

  Note that the gate signals PWC1 and PWC2 are generated so as not to be simultaneously at the Hi level (in other words, the switching Q1 and Q2 are not simultaneously turned on). Further, in order to prevent a short circuit due to a switching timing shift between the switching Q1 and Q2, a dead time (that is, a period in which both the switching Q1 and Q2 are turned off) is provided.

  Reactor current IL periodically rises and falls according to the switching timing of gate signals PWC1 and PWC2. Here, in particular, in the input voltage circuit 310 according to the present embodiment, the reactor current IL is sampled at the timing including the peak of the carrier signal (that is, times ta and tb in the figure). In this way, the reactor current IL can be sampled at two points that are increasing. That is, it is possible to sample the reactor current IL when the current flows to the switching element Q2 side (that is, the lower arm).

  Here, if the sampling value of the reactor current IL at time ta is Ia and the sampling value of the reactor current IL at time tb is Ib, the time change rate di / dt of the reactor current IL can be expressed by the following equation (1).

di / dt = (Ib−Ia) / (tb−ta) (1)
That is, the time change rate di / dt of the reactor current IL can be calculated as a value obtained by dividing the difference between the currents at the times ta and tb by the difference between the times ta and tb.

  The input voltage VL can be expressed by the following formula (2) using the above-described time change rate di / dt of the reactor current IL and the inductance value L of the reactor L1.

VL = L × di / dt (2)
That is, the input voltage VL can be calculated as a product of the inductance value L of the reactor L1 and the time change rate di / dt of the reactor current IL.

  Thus, if the reactor current IL and the inductance value L of the reactor L1 are known, the input voltage VL can be calculated reliably. Therefore, the value of the input voltage VL can be obtained even when a voltage sensor for detecting the input voltage VL is not provided as in the present embodiment. Therefore, even if the value of the input voltage VL is not directly detected, it is possible to suitably control the converter 12 using the indirectly estimated input voltage VL.

  As described above, according to the voltage conversion device according to the first embodiment, it is not necessary to provide a voltage sensor dedicated to the input voltage VL, so that the increase in cost and the complexity of the device configuration can be reduced.

Second Embodiment
Next, the voltage converter according to the second embodiment will be described. Note that the second embodiment differs from the first embodiment described above only in part of the configuration, and the other parts are substantially the same. For this reason, below, a different part from 1st Embodiment is demonstrated in detail, and description is abbreviate | omitted suitably about the overlapping part.

  First, the overall configuration of a vehicle on which the voltage conversion device according to the second embodiment is mounted will be described with reference to FIG. FIG. 5 is a schematic diagram showing the overall configuration of a vehicle on which the voltage conversion device according to the second embodiment is mounted.

  In FIG. 5, in the vehicle 100 according to the second embodiment, the input voltage VL (that is, the voltage before boosting) is detected by the voltage sensor 10. The detected input voltage VL is output to the ECU 30.

  On the other hand, the voltage sensor 13 (see FIG. 1) that detects the output voltage VH (that is, the boosted voltage) provided in the first embodiment is provided in the vehicle 100 according to the second embodiment. Absent. Therefore, the output voltage VH is not input to the ECU 30.

  Next, a specific configuration of the ECU according to the second embodiment will be described with reference to FIG. FIG. 6 is a block diagram showing the configuration of the ECU according to the second embodiment. In FIG. 6, for convenience of explanation, only the parts deeply related to the present embodiment are shown among the parts provided in the ECU 30, and other detailed parts are appropriately omitted.

  6, the ECU 30 includes an output voltage estimation circuit 360, a voltage control unit 320, a current control unit 330, a gate signal output circuit 340, and a carrier signal output unit 350.

  The output voltage estimation circuit 360 includes an input reactor current IL (ie, a current value detected by the current sensor 18) and an input voltage VL (ie, a voltage value detected by the voltage sensor 10), and a reactor stored in advance. The boosted DC voltage VH is estimated based on the inductance value of L1. The estimated DC voltage VH is output to the voltage control unit 320.

  Voltage control unit 320 calculates a voltage deviation based on input voltage VL and DC voltage VH estimated by output voltage estimation circuit 360 to calculate reactor current command value ILREF. The calculated reactor current command value ILREF is output to the current control unit 330.

  The current control unit 330, the gate signal output circuit 340, and the carrier signal generation unit 350 have the same configuration as that of the first embodiment.

  Next, a specific configuration of the output voltage estimation circuit 360 included in the ECU 30 described above will be described with reference to FIG. FIG. 7 is a circuit diagram showing the configuration of the output voltage estimation circuit.

  In FIG. 7, the output voltage estimation circuit 360 includes an ADC 361, a sampling timing generation circuit 362, a current change rate calculation unit 363, and an output voltage calculation unit 364.

  The ADC 361 samples the value of the reactor current IL at a plurality of different timings and outputs it to the current change rate calculation unit 363. The ADC 361 samples the reactor current IL at a timing based on the timing signal input from the sampling timing generation circuit 362.

  Sampling timing generation circuit 362 generates a timing signal indicating the sampling timing of reactor current IL based on carrier signal CR. Specifically, the sampling timing generation circuit 362 generates a timing signal so that the sampling timing is within a predetermined range including the valley of the carrier signal CR.

  The current change rate calculation unit 363 is an example of the “change rate calculation means” of the present invention, and the time rate of change of the reactor current IL (in other words, the reactor current IL from the values of the reactor current IL sampled at a plurality of timings in the ADC 361). A time differential value dIL / dT of the current IL is calculated. A method for calculating the time change rate of the reactor current IL will be described in detail later.

  The output voltage calculation unit 364 is an example of the “voltage estimation unit” of the present invention, and calculates (estimates) the output voltage VH using the time change rate of the reactor current IL calculated by the current change rate calculation unit 363. . The output voltage calculation unit 364 receives the input voltage VL in addition to the time change rate of the reactor current IL. In addition, the output voltage calculation unit 364 stores in advance the inductance value of the reactor L1.

  As described above, the output voltage estimation circuit 360 estimates the output voltage VH by performing various calculations after sampling the reactor current L1 at the timing based on the carrier signal CR.

  Next, a specific operation when the output voltage VH is estimated in the output voltage estimation circuit 360 will be described with reference to FIG. 8 in addition to FIG. FIG. 8 is a timing chart showing the sampling timing of the IL according to the second embodiment.

  In FIG. 8, the reactor current IL periodically rises and falls according to the switching timing of the gate signals PWC1 and PWC2. Here, in particular, in the output voltage circuit 360 according to the present embodiment, the reactor current IL is sampled at a timing including the valley of the carrier signal (that is, at times tc and td in the figure). In this way, the reactor current IL can be sampled at two points that are falling. That is, the reactor current IL when the current flows to the switching element Q1 side (that is, the upper arm) can be sampled.

  Here, if the sampling value of the reactor current IL at time tc is Ic and the sampling value of the reactor current IL at time td is Id, the time change rate di / dt of the reactor current IL can be expressed by the following equation (3).

di / dt = (Id−Ic) / (td−tc) (3)
That is, the time change rate di / dt of the reactor current IL can be calculated as a value obtained by dividing the difference in current at times tc and td by the difference between times tc and td.

  The output voltage VH can be expressed by the following formula (4) using the above-described time change rate di / dt of the reactor current IL, the input voltage VL, and the inductance value L of the reactor L1.

VH = VL + L × di / dt (4)
That is, the output voltage VH can be calculated as a value obtained by adding the product of the inductance value L of the reactor L1 and the time rate of change di / dt of the reactor current IL to the input voltage VL.

  Thus, if the reactor current IL, the input voltage VL, and the inductance value L of the reactor L1 are known, the output voltage VH can be calculated reliably. Therefore, even when the voltage sensor for detecting the output voltage VH is not provided as in the present embodiment, the value of the output voltage VH can be obtained. Therefore, even when the value of the output voltage VH is not directly detected, it is possible to suitably control the converter 12 using the indirectly estimated output voltage VH.

  As described above, according to the voltage conversion apparatus according to the second embodiment, it is possible to reduce the increase in cost and the complexity of the apparatus configuration because it is not necessary to provide a voltage sensor dedicated to the output voltage VH.

  As can be seen from the relationship of the above formula (4), in the method of the second embodiment, when the output voltage VH is detected instead of the input voltage VL (that is, as shown in FIG. 1). In the configuration), it is possible to estimate the input voltage VL.

  Specifically, as long as the output voltage VH is detected, the current flows to the switching element Q1 side without sampling the reactor current IL when the current flows to the switching element Q2 side as in the first embodiment. The input voltage VL can be estimated by sampling the reactor current IL when it is flowing.

  In this case, the input voltage VL can be calculated using the following formula (5) obtained by modifying the formula (4).

VL = VH−L × di / dt (5)
That is, the input voltage VL can be calculated as a value obtained by subtracting the product of the inductance value L of the reactor L1 and the time change rate di / dt of the reactor current IL from the output voltage VH.

  As described above, the output voltage VH can be estimated only by the method of the second embodiment, but the input voltage VL can be estimated by the methods of both the first embodiment and the second embodiment.

  The present invention is not limited to the above-described embodiments, and can be appropriately changed without departing from the gist or concept of the invention that can be read from the claims and the entire specification. Is also included in the technical scope of the present invention.

  DESCRIPTION OF SYMBOLS 10 ... Voltage sensor, 12 ... Converter, 13 ... Voltage sensor, 18 ... Current sensor, 20 ... DC voltage generation part, 22, 23 ... Inverter, 28 ... Power storage device, 30 ... ECU, 40 ... Engine, 41 ... Power split mechanism , 42 ... drive wheels, 45 ... load device, 100 ... vehicle, 310 ... input voltage estimation circuit, 311 ... ADC, 312 ... sampling timing generation circuit, 313 ... current change rate calculation unit, 314 ... input voltage calculation unit, 320 ... Voltage control unit, 330 ... current control unit, 340 ... gate signal output circuit, 350 ... carrier signal generation unit, 360 ... output voltage estimation circuit, 361 ... ADC, 362 ... sampling timing generation circuit, 363 ... current change rate calculation unit, 364: Output voltage calculation unit, C2: Smoothing capacitor, D1, D2: Diode, IL: Reactor current, L1: Rear Torr, MG1, MG2 ... motor-generator, PWC ... gate signal, Q1, Q2 ... switching device, SR1, SR2 ... system relay.

Claims (2)

Reactor,
A first switching element and a second switching element respectively connected in series to the reactor;
Current detecting means for detecting a reactor current flowing through the reactor;
A rate-of-change calculating means for calculating a rate of change of the reactor current;
Using the rate of change of the reactor current and the inductance of the reactor, the input voltage input to the first switching element and the second switching element, and the output output from the first switching element and the second switching element Voltage estimation means for estimating one of the voltages , and
The current detection means detects the reactor current a plurality of times at a timing of a first predetermined range including a peak of a carrier signal that defines a switching timing of each of the first switching element and the second switching element,
The rate of change calculation means calculates the rate of change of the reactor current from a plurality of values detected at the timing of the first predetermined range,
The voltage estimating device estimates the input voltage using a change rate of the reactor current and an inductance of the reactor . Comprising input voltage detection means for detecting the input voltage;
The current detection means detects the reactor current a plurality of times at a second predetermined range including a trough of a carrier signal that defines a switching timing of each of the first switching element and the second switching element,
The change rate calculation means calculates the change rate of the reactor current from a plurality of values detected at the timing of the second predetermined range,
The voltage converter according to claim 1 , wherein the voltage estimation unit estimates the output voltage using a rate of change of the reactor current, an inductance of the reactor, and the input voltage.

Images