JP7019429B2 - Motor drive system, signal correction method and signal correction program in motor drive system - Google Patents

Description

The present invention relates to a motor drive system, a signal correction method and a signal correction program in the motor drive system.

An electric vehicle such as an electric motorcycle or an electric vehicle has a motor for driving wheels and a motor drive system for driving the motor. The motor drive system includes a DC power supply and a motor drive. The DC power supply device includes a battery (Li-ion battery or the like) and a battery management unit (Battery Management Unit: BMU). The motor drive device has a power conversion circuit that supplies AC power to the motor, and a power control unit (Power Control Unit: PCU) that controls the power conversion circuit and the like. The PCI may also be referred to as a PDU (Power Drive Unit) or an ECU (Electronic Control Unit). Since the battery of an electric vehicle has a large capacity, a large current of several hundred amperes is output from the DC power supply device (battery) to the motor drive device at the peak time such as during acceleration.

The battery management unit (BMU) and the power control unit (PCU) usually have the vehicle body as a common ground. Further, a communication line for wired communication is provided between the two, and a signal indicating the state of the DC power supply device or the like is transmitted from the battery management unit to the power control unit via this communication line.

In addition, Patent Document 1 describes that a narrow band filter, a level converter, and a noise filter are used in order to remove noise mixed in a pulse signal.

Japanese Unexamined Patent Publication No. 9-322347

By the way, the electric wires that electrically connect the DC power supply and the vehicle body, the electric wires that electrically connect the motor drive and the vehicle body, the electrical connection parts such as the connectors provided at both ends of these electric wires, and the vehicle body There is a small resistance (parasitic resistance). Due to the influence of this parasitic resistance, when a large current is output from the battery, the reference potential of the power control unit (first reference potential) and the reference potential of the battery management unit (second reference potential) are common grounds. It floats from the potential of.

As a result, a potential difference is generated between the first reference potential and the second reference potential, and this potential difference is superimposed on the signal transmitted from the battery management unit to the power control unit. Therefore, the signal may exceed the normal range, and communication between the battery management unit (DC power supply device) and the power control unit (motor drive device) may not be performed normally.

Therefore, the present invention relates to a motor drive system, a motor drive method, and a motor capable of normally communicating between a DC power supply device and a motor drive device even when a large current is output from the battery. The purpose is to provide a drive program.

The motor drive system according to the present invention is
The first ground terminal, the output terminal, the battery in which the negative electrode is electrically connected to the first ground terminal and the positive electrode is electrically connected to the output terminal, and the battery are managed. A DC power supply device having a battery management unit whose reference potential is the potential of the ground terminal of
A second ground terminal electrically connected to the first ground terminal via a common ground portion, an input terminal electrically connected to the output terminal, and DC power output from the DC power supply device. Is communicably connected to the battery management unit via a communication line with the power conversion unit that converts the power into AC power and supplies it to the motor, controls the power conversion unit, and uses the potential of the second ground terminal as a reference. A motor drive device having a power control unit as a potential, and
The power control unit
An input current value acquisition unit that acquires the value of the input current supplied from the DC power supply device, and
A parasitic resistance value acquisition unit that acquires the value of the parasitic resistance existing from the first ground terminal to the second ground terminal via the common ground unit, and
An offset voltage calculation unit that calculates an offset voltage based on the value of the input current and the value of the parasitic resistance, and
It is characterized by having a signal level correction unit that corrects the level of a signal transmitted from the battery management unit and received via the communication line based on the offset voltage.

Further, in the motor drive system,
The signal level correction unit may correct the level of the signal by subtracting the offset voltage from the signal.

Further, in the motor drive system,
The signal level correction unit may constantly correct the level of the signal while the power control unit drives the motor.

Further, in the motor drive system,
The motor drive device may further include a storage unit, and the parasitic resistance value acquisition unit may read out the parasitic resistance value stored in advance in the storage unit.

Further, in the motor drive system,
The offset voltage calculation unit may calculate the offset voltage by multiplying the value of the parasitic resistance by the value of the input current.

Further, in the motor drive system,
The power control unit
When the voltage of the communication line is 0V, it is determined that the communication between the battery management unit and the power control unit is in a disconnected state.
When the voltage of the communication line is higher than 0V and lower than the first threshold voltage, it is determined that the DC power supply device is in an abnormal state.
When the voltage of the communication line is higher than the second threshold voltage higher than the first threshold voltage, it is determined that the DC power supply device is in the standby state.
When receiving a pulse signal within the range between the first threshold voltage and the second threshold voltage, the DC power supply device may further have a state determination unit for determining that the DC power supply device is in a normal state.

Further, in the motor drive system,
The motor drive device has an internal switch having one end electrically connected to the input terminal and the other end electrically connected to the high potential side of the power conversion unit, and an input voltage for measuring the voltage of the input terminal. It also has a measuring unit
The power control unit
The voltage of the input terminal in the first state where the internal switch is on and the power conversion unit is operating, and the second state where the internal switch is on and the power conversion unit is stopped. The value of the parasitic resistance is calculated by obtaining the voltage difference from the voltage of the input terminal in the above and dividing the voltage difference by the value of the input current supplied from the DC power supply device in the first state. It may further have a parasitic resistance value calculation unit.

Further, in the motor drive system,
The input voltage measuring unit is
A first resistance element, one end of which is electrically connected to the other end of the internal switch,
It has a second resistance element, one end of which is electrically connected to the other end of the first resistance element and the other end of which is electrically connected to the second ground terminal.
The connection point between the first resistance element and the second resistance element may be electrically connected to the power control unit.

Further, in the motor drive system,
The motor is a motor for rotationally driving the wheels of the electric vehicle, and the common ground portion may be the vehicle body of the electric vehicle.

Further, in the motor drive system,
Further provided with a vehicle acceleration acquisition unit for acquiring the acceleration of the electric vehicle,
The signal level correction unit may correct the level of the signal based on the acceleration.

Further, in the motor drive system,
When the acceleration is a positive specified value or more, the signal level correction unit may correct the level of the signal by subtracting the offset voltage from the signal.

Further, in the motor drive system,
When the acceleration is less than a negative specified value, the signal level correction unit may correct the level of the signal by applying the offset voltage to the signal.

The signal correction method according to the present invention is
The first ground terminal, the output terminal, the battery in which the negative electrode is electrically connected to the first ground terminal and the positive electrode is electrically connected to the output terminal, and the battery are managed. A DC power supply device having a battery management unit whose reference potential is the potential of the ground terminal of
A second ground terminal electrically connected to the first ground terminal via a common ground portion, an input terminal electrically connected to the output terminal, and DC power output from the DC power supply device. Is communicably connected to the battery management unit via a communication line with the power conversion unit that converts the power into AC power and supplies it to the motor, controls the power conversion unit, and uses the potential of the second ground terminal as a reference. A motor drive device having a power control unit for electric potential,
It is a signal correction method in a motor drive system including.
The input current value acquisition unit of the power control unit acquires the value of the input current supplied from the DC power supply device.
The parasitic resistance value acquisition unit of the power control unit acquires the value of the parasitic resistance existing from the first ground terminal to the second ground terminal via the common ground terminal.
The offset voltage calculation unit of the power control unit calculates the offset voltage based on the value of the input current and the value of the parasitic resistance.
The signal level correction unit of the power control unit corrects the level of the signal transmitted from the battery management unit and received via the communication line based on the offset voltage.

The signal correction program according to the present invention is
The first ground terminal, the output terminal, the battery in which the negative electrode is electrically connected to the first ground terminal and the positive electrode is electrically connected to the output terminal, and the battery are managed. A DC power supply device having a battery management unit whose reference potential is the potential of the ground terminal of
A second ground terminal electrically connected to the first ground terminal via a common ground portion, an input terminal electrically connected to the output terminal, and DC power output from the DC power supply device. Is communicably connected to the battery management unit via a communication line with the power conversion unit that converts the power into AC power and supplies it to the motor, controls the power conversion unit, and uses the potential of the second ground terminal as a reference. A motor drive device having a power control unit for electric potential,
A signal correction program in a motor drive system comprising
Computer,
An input current value acquisition means for acquiring the value of the input current supplied from the DC power supply device,
Parasitic resistance value acquisition means for acquiring the value of the parasitic resistance existing from the first ground terminal to the second ground terminal via the common ground portion.
The level of the signal transmitted from the battery management unit and received via the communication line is set to the offset voltage by the offset voltage calculating means for calculating the offset voltage based on the value of the input current and the value of the parasitic resistance. Signal level correction means to correct based on,
To function as.

In the present invention, the level of the signal transmitted from the battery management unit and received via the communication line is corrected based on the offset voltage calculated based on the value of the input current and the value of the parasitic resistance. Thereby, according to the present invention, even when a large current is output from the battery, communication can be normally performed between the DC power supply device and the motor drive device.

It is a figure which shows the schematic structure of the motor drive system which concerns on 1st Embodiment of this invention. It is a functional block diagram of the power control unit which concerns on 1st Embodiment. It is a flowchart for calculating a parasitic resistance. It is a flowchart for performing the signal level correction and the state determination which concerns on 1st Embodiment. It is a waveform diagram of a pulse signal when the signal level is not corrected. It is a waveform diagram of a pulse signal when the signal level is corrected. It is a flowchart which shows the detail of a state determination. It is a functional block diagram of the power control unit which concerns on 2nd Embodiment. It is a flowchart for performing the signal level correction and the state determination which concerns on 2nd Embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each figure, the same reference numerals are given to the components having the same functions.

(First Embodiment)
The motor drive system according to the first embodiment will be described.

The motor drive system 1 according to the present embodiment is a system for driving an AC motor such as a three-phase motor. As shown in FIG. 1, the motor drive system 1 includes a DC power supply device 10 that outputs DC power, and a motor drive device 20 that converts DC power into AC power to drive the motor 30.

The DC power supply device 10 has a ground terminal 10a (first ground terminal), an output terminal 10b, a battery 11, and a battery management unit 12 (BMU). In the battery 11, the negative electrode is electrically connected to the ground terminal 10a, and the positive electrode is electrically connected to the output terminal 10b. This battery is, for example, a lithium ion battery, but may be another battery.

The battery management unit 12 is a unit that manages the battery 11. The battery management unit 12 grasps the state of charge (SOC) of the battery 11. As shown in FIG. 1, the battery management unit 12 uses the potential of the ground terminal 10a as a reference potential (ground).
The battery management unit 12 is connected to the power control unit 22 of the motor drive device 20 via the communication line 40, and is configured to be able to transmit information to the motor drive device 20. Specifically, when the DC power supply device 10 is in the normal state, the battery management unit 12 is a pulse signal in the range of the threshold voltage Vth1 (first threshold voltage) or more and the threshold voltage Vth2 (second threshold voltage) or less. To send. Further, the battery management unit 12 transmits a DC signal (L level signal) having a voltage higher than 0 V and lower than the threshold voltage Vth when the DC power supply device 10 is in an abnormal state. When the DC power supply device 10 is in the standby state, the battery management unit 12 transmits a DC signal (H level signal) having a voltage higher than the threshold voltage Vth2.

The motor drive device 20 includes a ground terminal 20a (second ground terminal), an input terminal 20b electrically connected to the output terminal 10b, a power conversion unit 21, a power control unit 22, a storage unit 23, and the like. It has an internal switch 24 and an input voltage measuring unit 25. The ground terminal 20a is electrically connected to the ground terminal 10a via the common ground portion 50.

The power conversion unit 21 converts the DC power output from the DC power supply device 10 into AC power and supplies it to the motor 30. That is, the DC power supplied from the battery 11 via the output terminal 10b of the DC power supply device 10 and the input terminal 20b of the motor drive device 20 is converted into AC power by the power conversion unit 21 and supplied to the motor 30.

As shown in FIG. 1, the power conversion unit 21 is configured by a three-phase full bridge circuit. The semiconductor switches Q1, Q3 and Q5 are high-side switches, and the semiconductor switches Q2, Q4 and Q6 are low-side switches. The semiconductor switches Q1 to Q6 are, for example, MOSFETs, IGBTs, or the like. The control terminals of the semiconductor switches Q1 to Q6 are electrically connected to the power control unit 22 by a signal line (not shown). A smoothing capacitor C is provided at the input unit of the power conversion unit 21.

The power control unit 22 is configured to control the power conversion unit 21. More specifically, the power control unit 22 controls the power conversion unit 21 to operate the motor 30 at a desired torque and rotation speed.

As shown in FIG. 1, the power control unit 22 is communicably connected to the battery management unit 12 via the communication line 40. The communication line 40 is one communication line, for example, a copper wire. The power control unit 22 uses the potential of the ground terminal 20a as a reference potential.

The storage unit 23 stores information used by the power control unit 22 (for example, a value of parasitic resistance described later). Further, the storage unit 23 may store a program for operating the power control unit 22. The storage unit 23 is, for example, a non-volatile semiconductor memory, but is not limited thereto.

As shown in FIG. 1, the internal switch 24 is a switch in which one end is electrically connected to the input terminal 20b and the other end is electrically connected to the high potential side of the power conversion unit 21. The internal switch 24 is, for example, a mechanical switch such as a relay or a contactor. The internal switch 24 is on / off controlled by the power control unit 22.

The input voltage measuring unit 25 measures the voltage (input voltage) of the input terminal 20b. As shown in FIG. 1, the input voltage measuring unit 25 is composed of, for example, resistance elements R1 and R2 connected in series. That is, the input voltage measuring unit 25 is electrically connected to the resistance element R1 (first resistance element) having one end electrically connected to the other end of the internal switch 24 and one end electrically connected to the other end of the resistance element R1. The other end has a resistance element R2 (second resistance element) electrically connected to the ground terminal 20a. The connection point N between the resistance element R1 and the resistance element R2 is electrically connected to the power control unit 22. The power control unit 22 grasps the voltage of the input terminal 20b based on the voltage of the connection point N.

<Power control unit>
Next, with reference to FIG. 2, the details of the power control unit 22 according to the present embodiment will be described.

The power control unit 22 includes an input current value acquisition unit 221, a parasitic resistance value acquisition unit 222, an offset voltage calculation unit 223, a signal level correction unit 224, a state determination unit 225, and a parasitic resistance value calculation unit 226. have.

The input current value acquisition unit 221 acquires the value I of the input current supplied from the DC power supply device 10. For example, the input current value acquisition unit 221 acquires the current value measured by an ammeter (not shown) provided near the input terminal 20b. Alternatively, the input current value acquisition unit 221 may calculate the input current based on the line voltage of each phase of the motor 30, or the output current value of the battery 11 from the battery management unit 12 of the DC power supply device 10. (That is, the value I of the input current) may be acquired via a communication line (not shown) different from the communication line 40. Alternatively, the input current value acquisition unit 221 examines the relationship between the rotation speed of the motor 30 and the input current value I in advance and stores it in the storage unit 23 as a map, and the input current value acquisition unit 221 is the motor 30. And the value of the input current estimated based on the map may be acquired.

The parasitic resistance value acquisition unit 222 acquires the value r of the parasitic resistance existing from the ground terminal 10a to the ground terminal 20a via the common ground unit 50. Here, the "parasitic resistance" is a small resistance existing from the ground terminal 10a to the ground terminal 20a (for example, on the order of several milliΩ), and is a resistance of an electric wire or a resistance due to a connection component such as a connector. The resistance of the solder portion and the resistance of the common ground portion 50 are included. The parasitic resistance value acquisition unit 222 reads out the parasitic resistance value r stored in advance in the storage unit 23.

The offset voltage calculation unit 223 calculates the offset voltage ΔV based on the input current value I and the parasitic resistance value r. More specifically, the offset voltage calculation unit 223 calculates the offset voltage ΔV by multiplying the value r of the parasitic resistance by the value I of the input current.

The signal level correction unit 224 corrects the level of the signal transmitted from the battery management unit 12 and received via the communication line 40 based on the offset voltage ΔV. More specifically, the signal level correction unit 224 corrects the signal level by subtracting the offset voltage ΔV from the received signal.

The signal level correction unit 224 constantly corrects the level of the signal received via the communication line 40 while the power control unit 22 drives the motor 30. As a result, the signal level can be corrected quickly in response to changes in the input current.

The state determination unit 225 determines the state of the DC power supply device 10, the communication state by the communication line 40, and the like based on the voltage of the communication line 40. Specifically, when the voltage of the communication line 40 is 0V, the state determination unit 225 determines that the communication between the battery management unit 12 and the power control unit 22 is in a disconnected state. Further, when the voltage of the communication line 40 is higher than 0V and lower than the threshold voltage Vth1, it is determined that the DC power supply device 10 is in an abnormal state. When receiving a pulse signal within the range between the threshold voltage Vth1 and the threshold voltage Vth2, it is determined that the DC power supply device 10 is in a normal state. When the voltage of the communication line 40 is higher than the threshold voltage Vth2, it is determined that the DC power supply device 10 is in the standby state. This threshold voltage Vth2 is higher than the threshold voltage Vth1.

The parasitic resistance value calculation unit 226 calculates the parasitic resistance value r. Specifically, the parasitic resistance value calculation unit 226 has a voltage of the input terminal 20b (first input voltage) when the internal switch 24 is on and a voltage of the input terminal 20b (second input voltage) when the internal switch 24 is off. Obtain the voltage difference from the input voltage). Then, the parasitic resistance value calculation unit 226 calculates the parasitic resistance value by dividing the voltage difference by the value of the input current supplied from the DC power supply device 10 in the ON state. Then, the parasitic resistance value calculation unit 226 stores the calculated resistance value in the storage unit 23. The calculation of the parasitic resistance value is performed before the motor drive system 1 is used (for example, at the time of shipment from the factory).

<Flow of calculation of parasitic resistance value>
Here, the calculation flow of the parasitic resistance value will be described in detail with reference to FIG.

First, the power control unit 22 turns on the internal switch 24 of the motor drive device 20 to operate the power conversion unit 21 (step S11).

Next, the value of the input voltage (first input voltage) of the motor drive device 20 is acquired (step S12). The value of the input voltage is calculated based on the voltage of the connection point N of the input voltage measuring unit 25.

Next, the input current value acquisition unit 221 acquires the value of the input current of the motor drive device 20 (step S13).

Next, the power control unit 22 stops the power conversion unit 21 of the motor drive device 20 (step S14).

Next, the value of the input voltage (second input voltage) of the motor drive device is acquired (step S15). The value of the input voltage is calculated based on the voltage of the connection point N of the input voltage measuring unit 25.

Next, the parasitic resistance value calculation unit 226 obtains a voltage difference between the first input voltage acquired in step S12 and the second input voltage acquired in step S15 (step S16).

Next, the parasitic resistance value calculation unit 226 calculates the parasitic resistance value by dividing the voltage difference obtained in step S16 by the input current acquired in step S13 (step S17).

Next, the parasitic resistance value calculation unit 226 stores the parasitic resistance value calculated in step S17 in the storage unit 23 (step S18). After that, the power control unit 22 may turn off the internal switch 24 of the motor drive device 20.

As described above, the parasitic resistance value calculation unit 226 has the voltage of the input terminal 20b in the first state in which the internal switch 24 is on and the power conversion unit 21 is operating, and the internal switch 24 is on. The voltage difference between the voltage of the input terminal 20b and the voltage of the input terminal 20b in the second state in which the power conversion unit 21 is stopped is obtained, and the voltage difference is the value of the input current supplied from the DC power supply device 10 in the first state. Calculate the value of parasitic resistance by dividing by.

<Processing flow for signal level correction and status determination>
Here, an example of the signal level correction processing flow according to the first embodiment will be described in detail with reference to FIG.

First, the power control unit 22 determines whether or not the motor 30 is being driven (step S21). When the motor 30 is being driven (S21: Yes), the input current value acquisition unit 221 acquires the value of the input current of the motor drive device 20 (step S22).

Next, the power control unit 22 acquires the value of the parasitic resistance (step S23). Specifically, the value of the parasitic resistance is read from the storage unit 23.

Next, the offset voltage calculation unit 223 of the power control unit 22 calculates the offset voltage ΔV based on the value of the input current acquired in step S22 and the value of the parasitic resistance acquired in step S23 (step S24). ).

Next, the signal level correction unit 224 of the power control unit 22 corrects the level of the signal received from the communication line 40 based on the offset voltage ΔV calculated in step S24 (step S25). In this step, the signal level correction unit 224 corrects the signal level by subtracting the offset voltage ΔV from the received signal. As shown in FIGS. 5 and 6, even when the level (offset) of the pulse signal changes due to the influence of parasitic resistance, the pulse signal is kept in the normal range (threshold voltage Vth1 or more, Vth2 or less range) by level correction. Can be corrected to. 5 and 6 are examples of pulse signal waveforms when the output current of the DC power supply device 10 increases after time t1.

Next, the state determination unit 225 of the power control unit 22 determines the state of the DC power supply device 10 and the state of communication by the communication line 40 (step S26). The processing content of the state determination unit 225 in this step will be described in detail with reference to the flowchart of FIG.

The state determination unit 225 determines whether or not the potential of the communication line 40 is 0V (step S31). When the potential of the communication line 40 is 0V (S31: Yes), the state determination unit 225 determines that the communication between the battery management unit 12 and the power control unit 22 is in a disconnected state (step S32). On the other hand, when the potential of the communication line 40 is not 0 V (S31: No), the state determination unit 225 determines whether or not the L level signal is received (step S33). Here, the L level signal is a DC signal having a voltage higher than 0V and lower than the threshold voltage Vth1.

When the L level signal is received (S33: Yes), the state determination unit 225 determines that the DC power supply device 10 is in an abnormal state (step S34). On the other hand, when the L level signal is not received (S33: No), the state determination unit 225 determines whether or not the H level signal is received (step S35). Here, the H level signal is a DC signal having a voltage higher than the threshold voltage Vth2.

When the H level signal is received (S35: Yes), the state determination unit 225 determines that the DC power supply device 10 is in the standby state (step S36). On the other hand, when the H level signal is not received (S35: No), the state determination unit 225 determines whether or not the pulse signal in the range of the threshold voltage Vth1 or more and the threshold voltage Vth2 or less is received (step). S37). When such a pulse signal is received (S37: Yes), the state determination unit 225 determines that the DC power supply device 10 is in a normal state (step S38). On the other hand, when the pulse signal is not received (S37: No), the state determination unit 225 determines that another abnormality has occurred (step S39).

According to the above processing flow, the potential difference between the reference potential of the DC power supply device 10 and the motor drive device 20 is corrected in step S25, and then the state of the DC power supply device 10 is determined in step S26. Therefore, it is possible to prevent erroneous determination of the state of the DC power supply device 10 and the state of communication by the communication line 40.

The above flow of state determination is only an example. For example, the execution order of the determination steps of steps S31, S33, S35, and S37 can be changed.

As described above, in the first embodiment, the level of the signal transmitted from the battery management unit 12 and received via the communication line 40 is calculated based on the input current value I and the parasitic resistance value r. The correction is made based on the offset voltage ΔV. As a result, even when a large current is output from the battery 11, communication can be normally performed between the DC power supply device 10 and the motor drive device 20.

(Second embodiment)
A second embodiment of the present invention will be described. The motor drive system according to the present embodiment is applied to an electric vehicle such as an electric vehicle or an electric motorcycle. Hereinafter, the second embodiment will be described with a focus on the differences from the first embodiment.

The schematic configuration of the motor drive system according to the present embodiment is the same as that of the first embodiment (see FIG. 1). However, in the present embodiment, the motor 30 is a motor for rotationally driving the wheels of the electric vehicle, and the common ground portion 50 is the vehicle body (chassis) of the electric vehicle.

As shown in FIG. 8, the power control unit 22A according to the present embodiment has the configuration of the power control unit 22 according to the first embodiment (input current value acquisition unit 221, parasitic resistance value acquisition unit 222, offset voltage calculation unit). In addition to 223, a signal level correction unit 224, a state determination unit 225, and a parasitic resistance value calculation unit 226), it further has a vehicle acceleration acquisition unit 227.

The vehicle acceleration acquisition unit 227 acquires the acceleration of the electric vehicle based on the information of the rotation speed of the motor 30 or the accelerator opening degree. The vehicle acceleration acquisition unit 227 obtains the acceleration of the electric vehicle based on the signal received from the accelerator position sensor that detects the accelerator operation amount set by the driver's accelerator operation and the angle sensor that detects the rotation angle of the motor 30. calculate.

The signal level correction unit 224 corrects the level of the signal received from the communication line 40 based on the acceleration of the electric vehicle acquired by the vehicle acceleration acquisition unit 227. For example, the signal level correction unit 224 signals by subtracting the offset voltage from the signal when the driver operates the accelerator to greatly increase the acceleration of the electric vehicle (that is, when the acceleration is equal to or more than a positive specified value). Correct the level of. As a result, when a large current is output from the battery 11 and the difference in the reference potential between the battery management unit 12 and the power control unit 22 increases, the signal level can be corrected.

Further, the signal level correction unit 224 may correct the signal level when the regenerative brake is operated and the acceleration of the electric vehicle is significantly reduced (that is, when the acceleration is less than a negative specified value). In this case, the signal level correction unit 224 corrects the signal level by applying an offset voltage to the received signal. As a result, even when the current generated by the regenerative operation of the motor 30 is output from the motor drive device 20 to the DC power supply device 10 (that is, when a large current is input to the battery 11), the DC power supply device Normal communication can be performed between the 10 and the motor drive device 20.

<Processing flow for signal level correction and status determination>
Next, with reference to FIG. 9, the processing flow of signal level correction according to the second embodiment will be described in detail.

First, the power control unit 22A determines whether or not the accelerator operation has been performed by the driver (step S41). This step is performed based on the signal received from the accelerator position sensor or the angle sensor. When it is determined that the accelerator operation has been performed (S41: Yes), the process of step S22 to step S26 is executed as described in the first embodiment. In step S41, it may be determined whether or not the regenerative braking operation has been performed.

As described above, in the second embodiment, since the signal level is corrected based on the offset voltage, even when a large current is output from the battery 11 by the accelerator operation of the electric vehicle, the DC power supply device 10 is used. Communication can be normally performed with the motor drive device 20. Further, according to the present embodiment, even when a large current is input to the battery 11 by the regenerative braking operation, the DC power supply device 10 and the motor drive device 20 can normally communicate with each other.

At least a part of the motor drive device 20 (power control units 22, 22A) described in the above-described embodiment may be configured by hardware or software. When configured by software, a program that realizes at least a part of the functions of the power control units 22 and 22A may be stored in a recording medium such as a flexible disk or a CD-ROM, read by a computer, and executed. The recording medium is not limited to a removable one such as a magnetic disk or an optical disk, and may be a fixed recording medium such as a hard disk device or a memory.

Further, a program that realizes at least a part of the functions of the power control units 22 and 22A may be distributed via a communication line (including wireless communication) such as the Internet. Further, the program may be encrypted, modulated, compressed, and distributed via a wired line or a wireless line such as the Internet, or stored in a recording medium.

Based on the above description, those skilled in the art may be able to conceive additional effects and various modifications of the present invention, but the embodiments of the present invention are not limited to the individual embodiments described above. .. Components across different embodiments may be combined as appropriate. Various additions, changes and partial deletions are possible without departing from the conceptual idea and purpose of the present invention derived from the contents specified in the claims and their equivalents.

1 Motor drive system 10 DC power supply 10a Ground terminal 10b Output terminal 11 Battery 12 Battery management unit (BMU)
20 Motor drive device 20a Ground terminal 20b Input terminal 21 Power conversion unit 22, 22A Power control unit 221 Input current value acquisition unit 222 Parasitic resistance value acquisition unit 223 Offset voltage calculation unit 224 Signal level correction unit 225 Condition determination unit 226 Parasitic resistance value Calculation unit 227 Vehicle acceleration acquisition unit 23 Storage unit 24 Internal switch 25 Input voltage measurement unit 40 Communication line 50 Common ground unit

Claims (10)

A motor drive system for driving electric vehicles,
The first ground terminal, the output terminal, the battery in which the negative electrode is electrically connected to the first ground terminal and the positive electrode is electrically connected to the output terminal, and the battery are managed. A DC power supply device having a battery management unit whose reference potential is the potential of the ground terminal of
A second ground terminal electrically connected to the first ground terminal via a common ground portion which is a vehicle body of the electric vehicle, an input terminal electrically connected to the output terminal, and a DC power supply. A power conversion unit that converts DC power output from the device into AC power and supplies it to a motor for rotationally driving the wheels of the electric vehicle is communicably connected to the battery management unit via a communication line. A motor driving device having a power control unit that controls the power conversion unit and uses the potential of the second ground terminal as a reference potential is provided.
The power control unit
A vehicle acceleration acquisition unit that acquires the acceleration of the electric vehicle, and
An input current value acquisition unit that acquires the value of the input current supplied from the DC power supply device, and
A parasitic resistance value acquisition unit that acquires the value of the parasitic resistance existing from the first ground terminal to the second ground terminal via the common ground unit, and
An offset voltage calculation unit that calculates an offset voltage based on the value of the input current and the value of the parasitic resistance, and
When the acceleration of the electric vehicle is equal to or higher than a positive specified value, the level of the signal is corrected by subtracting the offset voltage from the level of the signal transmitted from the battery management unit and received via the communication line. When the acceleration is less than a negative specified value, a signal level correction unit that corrects the level of the signal by applying the offset voltage to the level of the signal, and a signal level correction unit.
A motor drive system characterized by having. The motor drive system according to claim 1, wherein the signal level correction unit corrects the level of the signal by subtracting the offset voltage from the signal. The motor drive system according to claim 1 or 2, wherein the signal level correction unit constantly corrects the level of the signal while the power control unit drives the motor. The method according to any one of claims 1 to 3, wherein the motor driving device further includes a storage unit, and the parasitic resistance value acquisition unit reads out the parasitic resistance value stored in advance in the storage unit. Motor drive system. The motor drive system according to any one of claims 1 to 4, wherein the offset voltage calculation unit calculates the offset voltage by multiplying the value of the parasitic resistance by the value of the input current. The power control unit
When the voltage of the communication line is 0V, it is determined that the communication between the battery management unit and the power control unit is in a disconnected state.
When the voltage of the communication line is higher than 0V and lower than the first threshold voltage, it is determined that the DC power supply device is in an abnormal state.
When the voltage of the communication line is higher than the second threshold voltage higher than the first threshold voltage, it is determined that the DC power supply device is in the standby state.
When receiving a pulse signal within a range between the first threshold voltage and the second threshold voltage, the DC power supply device further includes a state determination unit for determining that the DC power supply device is in a normal state. The motor drive system according to any one of claims 1 to 5. The motor drive device has an internal switch having one end electrically connected to the input terminal and the other end electrically connected to the high potential side of the power conversion unit, and an input voltage for measuring the voltage of the input terminal. It also has a measuring unit
The power control unit
The voltage of the input terminal in the first state where the internal switch is on and the power conversion unit is operating, and the second state where the internal switch is on and the power conversion unit is stopped. The value of the parasitic resistance is calculated by obtaining the voltage difference from the voltage of the input terminal in the above and dividing the voltage difference by the value of the input current supplied from the DC power supply device in the first state. The motor drive system according to any one of claims 1 to 6, further comprising a parasitic resistance value calculation unit. The input voltage measuring unit is
A first resistance element, one end of which is electrically connected to the other end of the internal switch,
It has a second resistance element, one end of which is electrically connected to the other end of the first resistance element and the other end of which is electrically connected to the second ground terminal.
The motor drive system according to claim 7, wherein the connection point between the first resistance element and the second resistance element is electrically connected to the power control unit. A motor drive system for driving an electric vehicle, in which a negative electrode is electrically connected to a first ground terminal, an output terminal, and the first ground terminal, and a positive electrode is electrically connected to the output terminal. The first via a DC power supply device having a battery, a battery management unit that manages the battery and a battery management unit having a potential of the first ground terminal as a reference potential, and a common ground unit that is a vehicle body of the electric vehicle . The second ground terminal electrically connected to the ground terminal of 1, the input terminal electrically connected to the output terminal, and the DC power output from the DC power supply device are converted into AC power, and the above- mentioned A power conversion unit that supplies a motor for rotationally driving the wheels of an electric vehicle is communicably connected to the battery management unit via a communication line, controls the power conversion unit, and has a second ground terminal. It is a signal correction method in a motor drive system including a motor drive device having a power control unit having a potential as a reference potential.
The vehicle acceleration acquisition unit of the power control unit acquires the acceleration of the electric vehicle,
The input current value acquisition unit of the power control unit acquires the value of the input current supplied from the DC power supply device.
The parasitic resistance value acquisition unit of the power control unit acquires the value of the parasitic resistance existing from the first ground terminal to the second ground terminal via the common ground terminal.
The offset voltage calculation unit of the power control unit calculates the offset voltage based on the value of the input current and the value of the parasitic resistance.
When the acceleration of the electric vehicle is equal to or higher than a positive specified value, the signal level correction unit of the power control unit obtains the offset voltage from the level of the signal transmitted from the battery management unit and received via the communication line. A signal correction method characterized in that the level of the signal is corrected by subtraction, and when the acceleration is less than a negative specified value, the level of the signal is corrected by applying the offset voltage to the level of the signal. A motor drive system for driving an electric vehicle, in which a negative electrode is electrically connected to a first ground terminal, an output terminal, and the first ground terminal, and a positive electrode is electrically connected to the output terminal. The first via a DC power supply device having a battery, a battery management unit that manages the battery and a battery management unit having a potential of the first ground terminal as a reference potential, and a common ground unit that is a vehicle body of the electric vehicle . The second ground terminal electrically connected to the ground terminal of 1, the input terminal electrically connected to the output terminal, and the DC power output from the DC power supply device are converted into AC power, and the above- mentioned A power conversion unit that supplies a motor for rotationally driving the wheels of an electric vehicle is communicably connected to the battery management unit via a communication line, controls the power conversion unit, and has a second ground terminal. A signal correction program in a motor drive system including a motor drive device having a power control unit having a potential as a reference potential.
Computer,
The vehicle acceleration acquisition means for acquiring the acceleration of the electric vehicle and the vehicle acceleration acquisition means.
An input current value acquisition means for acquiring the value of the input current supplied from the DC power supply device,
Parasitic resistance value acquisition means for acquiring the value of the parasitic resistance existing from the first ground terminal to the second ground terminal via the common ground portion.
An offset voltage calculating means for calculating an offset voltage based on the value of the input current and the value of the parasitic resistance, and
When the acceleration of the electric vehicle is equal to or higher than a positive specified value, the level of the signal is corrected by subtracting the offset voltage from the level of the signal transmitted from the battery management unit and received via the communication line. A signal level correction means that corrects the level of the signal by applying the offset voltage to the level of the signal when the acceleration is less than a negative specified value .
A signal correction program that functions as.

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