JP2013252019A - On-vehicle device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an on-vehicle device in which power factor can be improved without providing a dedicated apparatus on the outside of a three-phase inverter in an on-vehicle device including the three-phase inverter.SOLUTION: An on-vehicle device 1 includes a running inverter 12 provided between a running motor 11 and a battery 2, and a cargo handling inverter 22 provided between a cargo handling motor 21 and the battery 2. Resistors R1, R2, R11, R12 for measuring the midpoint voltage are connected between the midpoints of third switching elements Q3, Q13 and fourth switching elements Q4, Q14 and the negative electrode of the battery 2. A controller 40 performs power factor improvement based on the midpoint voltages measured by the resistors R1, R2, R11, R12 for measuring the midpoint voltage.

Description

  The present invention relates to an in-vehicle device.

  For example, in a vehicle equipped with a large battery as a power source such as an electric vehicle, it is necessary to charge the battery when the charge amount of the battery becomes a predetermined amount or less. At this time, in order to charge the battery efficiently, it is necessary to improve the power factor, and in order to improve the power factor, it is necessary to control the input current waveform into a sine wave having the same phase as the voltage waveform. Therefore, in order to control the input current waveform to a sine wave having the same phase as the voltage waveform, a control device is known that calculates the phase of the input power supply and controls the input current (for example, Patent Document 1).

  In Patent Document 1, an inverter and a transformer are connected to the AC power source, and a phase detector is connected to the transformer. Further, a phase calculation processing unit and a phase angle detection processing unit are connected to the phase detection device, and a current control calculation processing unit is connected to the phase angle detection processing unit. The current control arithmetic processing unit is connected to the inverter through a gate circuit. The phase detection device converts the three-phase voltage signal detected by the transformer into two phases, digitally converts one of the two-phase power synchronization signals, and outputs a phase angle detection processing unit and It is sent to the phase calculation processing unit. The phase calculation processing unit derives the other power supply synchronization signal from one power supply synchronization signal. Then, the phase calculation processing unit sends a power supply synchronization signal to the phase angle detection processing unit. The phase angle detection processing unit detects the phase of the power supply synchronization signal from the power supply synchronization signal and sends it to the current control calculation processing unit. The current control arithmetic processing unit controls the input current by controlling the switching operation of the inverter device via the gate circuit based on the phase of the power supply synchronization signal.

JP-A-8-70578

By the way, in Patent Document 1, in order to detect the phase of the input power supply, the power supply phase signal must be detected for one phase, and a phase detection device for detecting the phase is required outside.
The present invention has been made paying attention to such problems existing in the prior art, and the purpose thereof is to provide a dedicated device outside the three-phase inverter in the in-vehicle device having the three-phase inverter. An object of the present invention is to provide an in-vehicle device that can improve the power factor.

  In order to solve the above-mentioned problems, the invention described in claim 1 is a three-phase inverter provided between a three-phase motor and a battery, a three-phase upper arm switching element and a lower arm for the three-phase inverter. A first control means for driving the three-phase motor by PWM control of the switching element; a midpoint of any one-phase upper arm switching element and lower arm switching element in the three-phase inverter; and a negative electrode of the battery A switching element for upper arm and lower arm switching in any one phase in the three-phase inverter, using a resistance for measuring the midpoint voltage connected between and a coil of the three-phase motor as a charging inductor. A second control means for charging the battery by PWM-controlling the element; and a midpoint voltage measured by the midpoint voltage measurement resistor. And controlling the switching device for the upper arm and the switching device for the lower arm so as to reduce the phase difference between the input voltage waveform in one phase of the three-phase inverter and the input current waveform in one phase of the three-phase inverter. The gist is that the third control means for improving the power factor is provided.

  According to this, from the resistance for the midpoint voltage measurement connected between the middle point of the switching element for the upper arm and the switching element for the lower arm of any one phase in the three-phase inverter and the negative electrode of the battery, The midpoint voltage of the switching element for the lower arm and the switching element for the lower arm can be measured. The third control means reduces the phase difference between the input voltage in one phase of the three-phase inverter and the input current in one phase of the three-phase inverter based on the midpoint voltage measured by the midpoint voltage measurement resistor. Thus, the switching device for the upper arm and the switching device for the lower arm for charging are controlled. The midpoint voltage is measured by the internal resistance (resistance for midpoint voltage measurement) of the three-phase inverter. For this reason, in a vehicle-mounted device provided with a three-phase inverter, the power factor can be improved without providing a dedicated device outside the three-phase inverter.

  According to a second aspect of the present invention, the midpoint voltage measurement resistor includes a midpoint between the switching element for the upper arm and the switching element for the lower arm that are PWM-controlled when the battery is charged by the second control unit, It is good also as a structure connected between the negative electrodes of a battery.

  4. The midpoint voltage measuring resistor according to claim 3, wherein the middle point voltage measuring resistor is not PWM-controlled when the battery is charged by the second control means, and the middle point of the upper arm switching element, the lower arm switching element, and the battery It is good also as a structure connected between these negative electrodes.

  The first three-phase motor and the second three-phase motor are provided as the three-phase motor, and the first three-phase inverter is connected to the first three-phase motor. A second three-phase inverter connected to the three-phase inverter and the second three-phase motor is provided, and the first three-phase inverter and the second three-phase inverter are connected to the secondary output of the Scott transformer. It is good also as a structure.

  According to the present invention, the power factor can be improved without providing an external device for detecting a phase or the like in an in-vehicle device including a three-phase inverter.

The circuit diagram of 1st Embodiment which actualized the vehicle-mounted apparatus of this invention to the battery forklift. Explanatory drawing of the current pathway at the time of charge. Explanatory drawing of the current pathway at the time of charge. The figure which shows the relationship between the input voltage in one phase of the three-phase inverter before switching element operation | movement, and the midpoint voltage measured by the resistance for midpoint voltage measurement. The figure which shows the relationship between the input voltage in one phase of the three-phase inverter during the switching element operation, the input current in one phase of the three-phase inverter, and the midpoint voltage measured by the midpoint voltage measurement resistor. The figure which shows the relationship between the input voltage in one phase of the three-phase inverter during the switching element operation, the input current in one phase of the three-phase inverter, and the midpoint voltage measured by the midpoint voltage measurement resistor. The circuit diagram of 2nd Embodiment which actualized the vehicle-mounted apparatus of this invention to the battery forklift. The figure which shows the relationship between the input voltage in one phase of the three-phase inverter during the switching element operation, the input current in one phase of the three-phase inverter, and the midpoint voltage measured by the midpoint voltage measurement resistor. The figure which shows the relationship between the input voltage in one phase of the three-phase inverter during the switching element operation, the input current in one phase of the three-phase inverter, and the midpoint voltage measured by the midpoint voltage measurement resistor.

(First embodiment)
A first embodiment in which the present invention is embodied in a battery forklift will be described below with reference to FIGS.

  As shown in FIG. 1, the battery forklift includes an in-vehicle device 1. The in-vehicle device 1 includes a traveling motor 11 as a first three-phase motor that uses a battery 2 as a power source, and a cargo handling motor 21 as a second three-phase motor. A traveling inverter 12 as a first three-phase inverter is provided between the traveling motor 11 and the battery 2, and a second three-phase inverter is disposed between the cargo handling motor 21 and the battery 2. The cargo handling inverter 22 is provided.

  The in-vehicle device 1 includes a Scott transformer 13 connected to the three-phase AC power source 3. A traveling inverter 12 is connected to one secondary output 13 a of the Scott transformer 13 via a rectifier circuit 14, and a traveling motor 11 is connected to the traveling inverter 12. As the traveling motor 11, a three-phase AC motor in which coils U1, V1, W1 are delta-connected is used. A cargo handling inverter 22 is connected to the other secondary output 13 b of the Scott transformer 13 via a rectifier circuit 24, and a cargo handling motor 21 is connected to the cargo handling inverter 22. As the cargo handling motor 21, a three-phase AC motor in which coils U2, V2, and W2 are delta-connected is used.

  The rectifier circuit 14 is constituted by a series circuit of two diodes D1 and D2, and a terminal 18a of one secondary output 13a of the Scott transformer 13 is connected to a connection point between the diodes D1 and D2. The positive side of the rectifier circuit 14 is connected to the positive electrode of the battery 2, and the negative side of the rectifier circuit 14 is connected to the negative electrode of the battery 2.

  The traveling inverter 12 includes a first switching element Q1, a third switching element Q3, a fifth switching element Q5 as three-phase upper arm switching elements, and a second switching as a lower arm switching element. A three-phase inverter including an element Q2, a fourth switching element Q4, and a sixth switching element Q6 is used. MOSFETs are used for the switching elements Q1 to Q6. The first switching element Q1 and the second switching element Q2, the third switching element Q3 and the fourth switching element Q4, the fifth switching element Q5 and the sixth switching element Q6 are respectively connected in series. The drains of switching elements Q1, Q3, and Q5 are connected to the positive electrode of battery 2, respectively, and the sources of switching elements Q2, Q4, and Q6 are connected to the negative electrode of battery 2, respectively. Parasitic diodes D are connected in antiparallel between the drains and sources of the switching elements Q1 to Q6, that is, in a state where the cathode corresponds to the drain and the anode corresponds to the source.

  The midpoint of the first switching element Q1 and the second switching element Q2 (the connection point between the source of the first switching element Q1 and the drain of the second switching element Q2) is the coil U1 and the coil V1 of the traveling motor 11. Connected to the connection point. The midpoint of the third switching element Q3 and the fourth switching element Q4 (the connection point between the source of the third switching element Q3 and the drain of the fourth switching element Q4) is connected to the traveling motor via the current sensor 31. 11 are connected to a connection point between the coil V1 and the coil W1. The midpoint of the fifth switching element Q5 and the sixth switching element Q6 (the connection point between the source of the fifth switching element Q5 and the drain of the sixth switching element Q6) is the coil U1 and the coil of the traveling motor 11 It is connected to the connection point with W1. The connection point between the source of the first switching element Q1 and the drain of the second switching element Q2 is a terminal opposite to the terminal 18a to which the rectifier circuit 14 of one secondary output 13a of the Scott transformer 13 is connected. 18b. Further, between the midpoint of the third switching element Q3 and the fourth switching element Q4 (the connection point between the source of the third switching element Q3 and the drain of the fourth switching element Q4) and the negative electrode of the battery 2. Are connected in series with resistors R1 and R2 for midpoint voltage measurement.

  The rectifier circuit 24 is constituted by a series circuit of two diodes D3 and D4, and a terminal 19a of the other secondary output 13b of the Scott transformer 13 is connected to a connection point between the diodes D3 and D4. The positive side of the rectifier circuit 24 is connected to the positive electrode of the battery 2, and the negative side of the rectifier circuit 24 is connected to the negative electrode of the battery 2.

  The cargo handling inverter 22 includes a first switching element Q11, a third switching element Q13, a fifth switching element Q15 as three-phase upper arm switching elements, and a second switching as a lower arm switching element. A three-phase inverter including an element Q12, a fourth switching element Q14, and a sixth switching element Q16 is used. MOSFETs are used for the switching elements Q11 to Q16. The first switching element Q11 and the second switching element Q12, the third switching element Q13 and the fourth switching element Q14, the fifth switching element Q15 and the sixth switching element Q16 are respectively connected in series. The drains of switching elements Q1, Q3, and Q5 are connected to the positive electrode of battery 2, respectively, and the sources of switching elements Q2, Q4, and Q6 are connected to the negative electrode of battery 2, respectively. Between the drain and source of each switching element Q11 to Q16, a parasitic diode D is connected in antiparallel, that is, in a state corresponding to the cathode corresponding to the drain and the anode corresponding to the source.

  The midpoint of the first switching element Q11 and the second switching element Q12 (the connection point between the source of the first switching element Q11 and the drain of the second switching element Q12) is the coil U2 and the coil V2 of the cargo handling motor 21. Connected to the connection point. The midpoint of the third switching element Q13 and the fourth switching element Q14 (the connection point between the source of the third switching element Q13 and the drain of the fourth switching element Q14) is connected to the motor for cargo handling via the current sensor 32. 21 is connected to a connection point between the coil V2 and the coil W2. The midpoint of the fifth switching element Q15 and the sixth switching element Q16 (the connection point between the source of the fifth switching element Q15 and the drain of the sixth switching element Q16) is the coil U2 and the coil of the cargo handling motor 21. It is connected to the connection point with W2. The connection point between the source of the first switching element Q11 and the drain of the second switching element Q12 is a terminal opposite to the terminal 19a to which the rectifier circuit 24 of the other secondary output 13b of the Scott transformer 13 is connected. 19b. Further, between the midpoint of the third switching element Q13 and the fourth switching element Q14 (the connection point between the source of the third switching element Q13 and the drain of the fourth switching element Q14) and the negative electrode of the battery 2. Are connected in series with resistors R11 and R12 for midpoint voltage measurement.

  The gates of the switching elements Q1 to Q6 and Q11 to Q16 are connected to the control device 40. The connection point between the resistors R1 and R2 and the connection point between the resistors R11 and R12 are connected to the control device 40. The control device 40 is connected to a current sensor 31 that detects a current flowing through the traveling motor 11 and a current sensor 32 that detects a current flowing through the cargo handling motor 21. The control device 40 includes a CPU and a memory (not shown), and a control program necessary for driving the traveling motor 11 and the cargo handling motor 21 is stored in the memory. The memory stores a control program necessary for controlling the switching elements Q1 to Q6 and Q11 to Q16 when the battery 2 is charged with the Scott transformer 13 connected to the three-phase AC power source 3. Yes. Further, the control device 40 can detect an input current waveform by a signal from the current sensors 31 and 32.

Next, the effect | action of the vehicle-mounted apparatus 1 of this embodiment is demonstrated.
The battery forklift is held in a state disconnected from the three-phase AC power supply 3 except when the battery 2 is charged. Then, the switching devices Q1 to Q6 of the traveling inverter 12 are controlled to be turned on / off by a command from the control device 40, whereby the direct current power of the battery 2 is converted into alternating current power and supplied to the traveling motor 11 for traveling. The motor 11 is driven. Further, the switching elements Q11 to Q16 of the cargo handling inverter 22 are turned on / off by a command from the control device 40, whereby the DC power of the battery 2 is converted into AC power and supplied to the cargo handling motor 21 for cargo handling. The motor 21 is driven. That is, the controller 40 controls the three-phase switching elements Q1 to Q6 in the traveling inverter 12 and the three-phase switching elements Q11 to Q16 in the cargo handling inverter 22 to drive the traveling motor 11 and the cargo handling motor 21. Functions as the first control means.

  When charging the battery 2, the Scott transformer 13 is held in a state where AC power is supplied from the three-phase AC power source 3. Specifically, the plug of the charging cable of the three-phase AC power supply 3 is connected to a power outlet provided on the forklift. Then, the control device 40 holds the switching elements Q1, Q2, Q5, Q6, Q11, Q12, Q15, Q16 of the traveling inverter 12 and the cargo handling inverter 22 in the off state, and the third switching elements Q3, Q13 and The fourth switching elements Q4 and Q14 are turned on / off. That is, the upper arm switching element and the lower arm switching element that are PWM-controlled when the control device 40 charges the battery 2 are the third switching elements Q3 and Q13 and the fourth switching elements Q4 and Q14. Further, the switching elements for the upper arm and the switching elements for the lower arm that are not PWM-controlled when the battery 2 is charged by the control device 40 are switching elements Q1, Q2, Q5, Q6, Q11, Q12, Q15, Q16.

  Then, the control device 40 switches the third switching elements Q3 and Q13 and the fourth switching elements Q4 and Q14 in the traveling inverter 12 and the cargo handling inverter 22 so that the coil V1 and the cargo handling of the traveling motor 11 are handled. The battery 2 is charged using the coil V2 of the motor 21 as a charging inductor. Therefore, in the present embodiment, the control device 40 functions as a second control unit.

  A path of current flowing through the in-vehicle device 1 when the battery 2 is charged will be described with reference to FIGS. 2 and 3, the current path for charging the battery 2 by controlling the switching elements Q3, Q4 of the traveling inverter 12 is described. However, the switching elements Q13, Q14 of the cargo handling inverter 22 are The same route is used when charging the battery 2 under control.

  As shown in FIG. 2, the third switching element Q3 is in the on state, the fourth switching element is in a state where electric power is output from the terminal 18a of one secondary output 13a of the Scott transformer 13 on the traveling inverter 12 side. When Q4 is in the off state, a current flows as shown by a broken line in FIG. That is, current flows through the path of the terminal 18a of the secondary output 13a → the diode D1 → the third switching element Q3 → the coil V1 of the traveling motor → the terminal 18b of the secondary output 13a, and electromagnetic energy is accumulated in the coil V1. . And when the 3rd switching element Q3 will be in an OFF state with the 4th switching element Q4 being an OFF state, the electromagnetic energy accumulate | stored in the coil V1 will become the electric current which flows through the path | route shown with a dashed-dotted line in FIG. That is, coil V1 of traveling motor 11 → terminal 18b of secondary output 13a → terminal 18a of single phase output 13a → diode D1 → battery 2 → parasitic diode D of fourth switching element Q4 → coil of traveling motor 11 The current flows through the path V1, and the battery 2 is charged.

  As shown in FIG. 3, when power is output from the terminal 18b of the secondary output 13a, the third switching element Q3 is in the off state and the fourth switching element Q4 is in the on state. Current flows as shown by the arrows. That is, a current flows through a path of the terminal 18b of the secondary output 13a → the coil V1 of the traveling motor 11 → the fourth switching element Q4 → the diode D2 → the terminal 18a of one of the secondary outputs 13a, and electromagnetic energy is applied to the coil V1. Accumulated. When the fourth switching element Q4 is turned off while the third switching element Q3 is in the off state, the electromagnetic energy accumulated in the coil V1 becomes a current flowing through the path indicated by the one-dot chain line arrow in FIG. . That is, the current flows through the coil V1 of the traveling motor 11 → the parasitic diode D of the third switching element Q3 → the battery 2 → the diode D2 → the terminal 18a of the secondary output 13a → the terminal 18b of the secondary output 13a. 2 is charged.

  Further, charging is performed also on the cargo handling inverter 22 side in the same manner as the traveling inverter 12. Specifically, the secondary output 13a on the traveling inverter 12 side is the secondary output 13b, the terminals 18a and 18b are the terminals 19a and 19b, the third switching element Q3 is the third switching element Q13, and the fourth The switching element Q4 may be replaced with the fourth switching element Q14, and the diodes D1 and D2 may be replaced with the diodes D3 and D4, respectively.

  The control device 40 adjusts the input current waveform in one phase of the traveling inverter 12 to match the input voltage waveform in one phase of the traveling inverter 12, that is, the input voltage in one phase of the traveling inverter 12 and the traveling inverter 12. The third switching element Q3 and the fourth switching element Q4 are PWM-controlled so that the phase difference of the input current in one phase is reduced. Hereinafter, a detailed description will be given with reference to FIGS.

  As shown in FIG. 4, the control device 40 is measured by the midpoint voltage measurement resistors R1, R2, R11, and R12 before the operations of the third switching elements Q3 and Q13 and the fourth switching elements Q4 and Q14. The zero cross point of the input voltage waveform P1 is detected from the midpoint voltage. More specifically, when resistors R1, R2, R11, and R12 for midpoint voltage measurement are connected between the midpoint of the third switching elements Q3 and Q13 and the fourth switching elements Q4 and Q14 and the negative electrode of the battery 2, The midpoint voltage waveform P2 of the third switching elements Q3 and Q13 and the fourth switching elements Q4 and Q14 is a half-wave rectification waveform of the input voltage waveform P1 in one phase of each of the inverters 12 and 22. Then, in the midpoint voltage waveform P2, the timing tz1 when the midpoint voltage rises from 0 and the timing tz2 when the midpoint voltage becomes 0 are detected and stored in the memory. That is, the timings tz1 and tz2 that pass through the zero cross point of the input voltage waveform P1 can be obtained from the midpoint voltage waveform P2.

  As shown in FIG. 5, when there is no phase difference between the input voltage waveform P1 in one phase of each inverter 12, 22 and the input current waveform P3 in one phase of each inverter 12, 22, the zero cross point in the input current waveform P3 The timing of passing through coincides with the timings tz1 and tz2 of passing through the zero cross point of the input voltage waveform P1. At this time, the on-duty of the third switching elements Q3 and Q13 and the fourth switching elements Q4 and Q14 is long when the input current is increased, and is shortened when the input current is decreased. Further, the off-duty of the third switching elements Q3 and Q13 and the fourth switching elements Q4 and Q14 is shortened when the input current is increased, and is increased when the input current is decreased. Therefore, as shown by the midpoint voltage waveform P2 in FIG. 5, the midpoint voltage has a long timing t1 that is maintained at a high voltage when the input current is increased, and a timing t1 that is maintained at the high voltage when the input current is decreased. short. Further, in the midpoint voltage waveform P2, when the input current is increased, the timing t2 maintained at a low voltage is short, and when the input current is decreased, the timing t2 maintained at a low voltage is long.

  As shown in FIG. 6, when the frequency of the input voltage waveform P1 in one phase of each of the inverters 12 and 22 fluctuates or the phase is shifted, the timing of passing through the zero cross point is the timing with the shift of the input voltage waveform P1. tz3 and tz4, which deviate from the timings tz1 and tz2 in FIG. When the timing of passing through the zero cross point in the input voltage waveform P1 shifts, the timing t1 at which the midpoint voltage is maintained at a high voltage and the midpoint voltage near the timings tz3 and tz4 in the input voltage waveform P1. Is maintained at a low voltage at a timing t2 that is longer than when the phase of the input voltage waveform P1 is not shifted (compared to FIG. 5).

  And the control apparatus 40 is based on the midpoint voltage measured by resistance R1, R2, R11, R12 for midpoint voltage measurement, the input voltage waveform P1 in one phase of each inverter 12,22, each inverter 12, The switching elements Q3, Q4, Q13, and Q14 are controlled so that the phase difference of the input current waveform P3 in one phase of 22 is reduced. Therefore, in the present embodiment, the control device 40 functions as a third control unit.

  In this embodiment, the midpoint voltage by the midpoint voltage measurement resistors R1, R2, R11, and R12 is reflected in the switching operations of the third switching elements Q3 and Q13 and the fourth switching elements Q4 and Q14. ing. For this reason, the control device 40 does not monitor the midpoint voltage waveform P2, but based on the switching duty of the third switching elements Q3, Q13 and the fourth switching elements Q4, Q14, the input in one phase of each inverter 12,22. The switching elements Q3, Q4, Q13, and Q14 may be controlled so that the phase difference between the voltage and the input current in one phase of each inverter 12 and 22 is reduced.

Therefore, according to the above embodiment, the following effects can be obtained.
(1) The control device 40 performs power factor correction based on the midpoint voltage waveform P2 of the third switching elements Q3 and Q13 and the fourth switching elements Q4 and Q14. Specifically, the control device 40 includes the third switching elements Q3 and Q13 so that the phase difference between the input voltage in one phase of each inverter 12 and 22 and the input current in one phase of each inverter 12 and 22 is reduced. The fourth switching elements Q4 and Q14 are controlled. The midpoint voltages of the third switching elements Q3, Q13 and the fourth switching elements Q4, Q14 are measured by the internal resistances of the inverters 12, 22 (midpoint voltage measuring resistors R1, R2, R11, R12). The For this reason, in the vehicle-mounted apparatus 1 provided with each inverter 12 and 22, a power factor can be improved, without providing a dedicated apparatus outside each inverter 12 and 22. FIG.

  (2) The vehicle-mounted device 1 includes a traveling inverter 12 and a traveling motor 11, a cargo handling inverter 22, a cargo handling motor 21, and a Scott transformer 13. The inverters 12 and 22, the motors 11 and 21, and the Scott transformer 13 can be used to charge the battery 2. When the battery 2 is charged, the third switching element Q3 and the fourth switching element Q4 in the traveling inverter 12 and the third switching element Q13 and the fourth switching element Q14 in the cargo handling inverter 22 are switched. Thereby, the battery 2 can be charged with the coil V1 of the motor 11 for driving | running | working and the coil V2 of the motor 21 for cargo handling with the single-phase alternating current power input from the Scott transformer 13 as a charging inductor. At the time of charging, the current flowing through the battery 2 becomes a combined current of currents flowing through two current paths (current path flowing through the coil V1 of the traveling motor 11 and current path flowing through the coil V2 of the cargo handling motor 21). . The two sets of secondary outputs 13a and 13b of the Scott transformer 13 are not in phase and have a phase difference of 90 degrees. Therefore, compared with the case where the battery 2 is charged using a set of inverters and motors, the current flowing through the battery 2 can be flattened (ripple reduced).

(3) Moreover, compared with the case where it charges using either the traveling motor 11 or the cargo handling motor 21, the heat_generation | fever of each motor 11 and 21 is reduced and it is suitable.
(4) The Scott transformer 13 is connected to the three-phase AC power source 3, and the traveling inverter 12 and the cargo handling inverter 22 are connected to the secondary outputs 13 a and 13 b of the Scott transformer 13. For this reason, compared with the case where a transformer is connected to each of the inverters 12 and 22, two-phase single-phase AC power can be acquired from the three-phase AC power supply 3 with the addition of minimum components.
(Second Embodiment)
A second embodiment in which the present invention is embodied in a battery forklift will be described below with reference to FIGS. In the embodiments described below, the same components as those already described are denoted by the same reference numerals, and redundant description thereof is omitted or simplified.

  In FIG. 1, the resistors R1, R2, R11, and R12 for measuring the midpoint voltage are the third switching elements Q3 and Q13 and the fourth switching elements Q4 and Q14 that are PWM-controlled when the battery 2 is charged by the control device 40. Between the middle point of the battery and the negative electrode of the battery 2. In contrast, in the in-vehicle device 5 of the present embodiment shown in FIG. 7, the midpoint voltage measurement resistors R21, R22, R31, and R32 are the first switching elements that are not PWM-controlled when the control device 40 charges the battery 2. Q1 and Q11 are connected between the middle point of the second switching elements Q2 and Q12 and the negative electrode of the battery 2.

  That is, the midpoint of the first switching element Q1 and the second switching element Q2 of the traveling inverter 12 (the connection point between the source of the first switching element Q1 and the drain of the second switching element Q2) and the battery 2 Between the negative electrode, resistors R21 and R22 for measuring the midpoint voltage are connected in series. Further, the midpoint of the first switching element Q11 and the second switching element Q12 of the cargo handling inverter 22 (the connection point between the source of the first switching element Q11 and the drain of the second switching element Q12) and the battery 2 Between the negative electrode, resistors R31 and R32 for measuring the midpoint voltage are connected in series. Other configurations of the in-vehicle device 5 of the present embodiment are the same as those of the in-vehicle device 1 of the first embodiment.

Next, the effect | action of the vehicle-mounted apparatus 5 of this embodiment is demonstrated.
The control device 40 can drive the traveling motor 11 and the cargo handling motor 21 by PWM-controlling the switching elements of the inverters 12 and 22 as in the first embodiment. Similarly, the battery 2 can be charged using the coil V1 of the traveling motor 11 and the coil V2 of the cargo handling motor 21 as charging inductors.

  The control device 40 detects the zero crossing of the input voltage waveform from the midpoint voltage in a state before the inverters 12 and 22 start to operate. In addition, the detection method of timing tz21 and tz22 which passes a zero crossing point is the same as 1st Embodiment. That is, the connection location of the resistors R21, R22, R31, R32 for measuring the midpoint voltage is changed between the midpoint of the first switching elements Q1, Q11 and the second switching elements Q2, Q12 and the negative electrode of the battery 2. However, the control device 40 can detect a waveform as shown in FIG. 4, that is, a half-wave rectified waveform of the input voltage waveform P1. Then, from this input voltage waveform P1, the frequency and phase of the input voltage in one phase of each of the inverters 12 and 22 and the timings tz21 and tz22 that pass through the zero cross point are detected.

  As shown in FIG. 8, when there is no phase difference between the input voltage waveform P21 in one phase of each inverter 12, 22 and the input current waveform P22 in one phase of each inverter 12, 22, the first switching elements Q1, Q11 The midpoint voltage waveform P23 of the second switching elements Q2 and Q12 changes from a high voltage to a low voltage at a timing tz21 when the zero crossing point is passed. Further, the voltage is changed from a low voltage to a high voltage at timing tz22.

  As shown in FIG. 9, when the frequency of the input voltage waveform P21 in one phase of each of the inverters 12 and 22 fluctuates or the phase is shifted, the zero cross point of the input voltage waveform P21 is changed with the shift of the input voltage waveform P21. The passing timings are timings tz23 and tz24, which are deviated from the timings tz21 and tz22 in FIG. When the timing of passing through the zero cross point in the input voltage waveform P21 shifts, the midpoint voltage waveform P23 is maintained at a high voltage after the timing tz23 of passing through the zero cross point of the input voltage waveform P21. Similarly, the midpoint voltage waveform P23 is maintained at a low voltage after the timing tz24.

  The control device 40 detects the maintenance of the midpoint voltage and performs switching so that the phase difference between the input voltage waveform P21 in one phase of the inverters 12 and 22 and the input current waveform P22 in one phase of each of the inverters 12 and 22 is reduced. Elements Q3, Q4, Q13 and Q14 are controlled.

Therefore, according to the said embodiment, in addition to the effect (2)-(4) of 1st Embodiment, the following effects can be acquired.
(5) Resistors R21, R22, R31, R32 for measuring the midpoint voltage connected between the first switching elements Q1, Q11, the second switching elements Q2, Q12 and the negative electrode of the battery 2 that are not switched during charging. Therefore, even if the midpoint voltage of the first switching elements Q1, Q11 and the second switching elements Q2, Q12 is measured, the power factor can be improved.

In addition, you may change each said embodiment as follows.
The battery 2 may be charged using either the traveling inverter 12 or the cargo handling inverter 22.

  ○ Not only a vehicle equipped with two three-phase motors (traveling motor 11 and cargo handling motor 21) like a battery forklift, but a general electric equipped with one three-phase motor (for example, a traveling motor) You may apply to the vehicle-mounted apparatus of a motor vehicle.

An IGBT (insulated gate bipolar transistor) or a power bipolar transistor may be used as each of the switching elements Q1 to Q6 and Q11 to Q16.
The connection of the coils U1, V1, W1 of the traveling motor 11 and the coils U2, V2, W2 of the cargo handling motor 21 is not limited to the delta connection, and may be a star connection.

○ A transformer other than the Scott transformer 13 may be used.
○ Single-phase AC power may be directly input to each of the inverters 12 and 22 without using a transformer.

  P1, P21 ... Input voltage waveform, P3, P22 ... Input current waveform, Q1, Q2, Q3, Q4, Q5, Q6, Q11, Q12, Q13, Q14, Q15, Q16 ... Switching elements, R1, R2, R11, R12 , R21, R22, R31, R32 ... resistors for measuring the midpoint voltage, U1, U2, V1, V2, W1, W2 ... coils, 1 ... on-vehicle device, 2 ... battery, 11 ... travel motor, 12 ... travel Inverter, 13 ... Scott transformer, 13a, 13b ... secondary output, 21 ... cargo handling motor, 22 ... cargo handling inverter, 40 ... control device.

Claims (4)

A three-phase inverter provided between the three-phase motor and the battery;
First control means for driving the three-phase motor by PWM control of the three-phase upper arm switching element and the lower arm switching element in the three-phase inverter;
A midpoint voltage measuring resistor connected between the midpoint of the switching element for the upper arm and the switching element for the lower arm of any one phase in the three-phase inverter and the negative electrode of the battery;
Second control means for charging the battery by PWM controlling any one phase of the upper arm switching element and the lower arm switching element in the three-phase inverter using the coil of the three-phase motor as a charging inductor. When,
The phase difference between the input voltage waveform in one phase of the three-phase inverter and the input current waveform in one phase of the three-phase inverter is reduced based on the midpoint voltage measured by the midpoint voltage measurement resistor. An in-vehicle apparatus comprising a third control means for improving a power factor by controlling an upper arm switching element and a lower arm switching element for charging.   The midpoint voltage measurement resistor is connected between the middle point of the upper arm switching element and the lower arm switching element that are PWM-controlled when the battery is charged by the second control means, and the negative electrode of the battery. The in-vehicle device according to claim 1, wherein   The midpoint voltage measurement resistor is connected between the middle point of the upper arm switching element and the lower arm switching element that are not PWM-controlled when the battery is charged by the second control means, and the negative electrode of the battery. The in-vehicle device according to claim 1, wherein   The three-phase motor includes a first three-phase motor and a second three-phase motor, and the first three-phase inverter connected to the first three-phase motor as the three-phase inverter and the second three-phase motor. A second three-phase inverter connected to a phase motor is provided, and the first three-phase inverter and the second three-phase inverter are connected to a secondary output of a Scott transformer. 4. The on-vehicle device according to any one of 3 above.