Vehicle control unit and running body

Abstract

To provide a vehicle control unit that can effectively prevent an inverter circuit from being damaged when an electric two-wheel vehicle is running on a slope road while turning off an electric motor, and a running body.SOLUTION: A vehicle control unit, which is connected to a first power supply through a connector, comprises: an inverter circuit that drives an AC electric motor; a power supply for the inverter circuit; a control part that outputs a control signal for controlling rotation of the electric motor to the inverter circuit; and an internal power supply circuit having an enable terminal to which an input end of the inverter circuit is connected. The vehicle control unit is configured so that voltages that are induced when the electric motor rotates at predetermined rotation speed or higher activate the internal power supply circuit, with the connector opened. When the internal power supply circuit is activated with the connector opened, the control part activates the power supply for the inverter circuit and outputs a command signal for turning on switching elements of all arms in multiple phases to the inverter circuit.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a vehicle control unit used for a traveling body such as a two-wheeled vehicle or other three-wheeled vehicle having a motor as a driving source, and to such a traveling body.

Background Art

[0002] In recent years, the demand for two-wheeled vehicles with an electric motor using a throttle as a speed adjustment mechanism has been expanding. For example, Patent Document 1 describes an inverter circuit that enhances the functionality of motor control mounted on an electric two-wheeled vehicle.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In an electric two-wheeled vehicle, generally, an in-vehicle power supply can be charged with the regenerative power of an electric motor as a driving source. Due to such characteristics of an electric two-wheeled vehicle, a driver may act in such a way as to devise a riding method to reduce power consumption or increase charging efficiency. For example, the driver may start going down a slope with the main switch and start switch of the electric two-wheeled vehicle turned off, and turn on the switch when the speed reaches a certain level. That is, in order to reduce the power consumption of the electric two-wheeled vehicle, the driver may go down a slope without starting the electric motor of the electric two-wheeled vehicle. When the electric motor is not running and the electric motor is rotated excessively, a large induced voltage is generated, which may damage the inverter circuit and cause breakdown of the withstand voltage of the device. As a countermeasure against the breakdown of the device's withstand voltage, it is assumed that a device with a high withstand voltage is selected for the generated induced voltage, the connection with the motor is cut off and the three phases are shorted, or the motor size and winding shape are changed to lower the generated induced voltage. However, when a device with a high withstand voltage is selected, especially in the case of a driving device, the higher the withstand voltage, the higher the impedance, resulting in a higher cost. From the viewpoints of efficiency and cost, it does not become a system with advantages, and the superiority as an electric two-wheeler is impaired. Also, the method of cutting off the connection with the motor can be said to be a very effective method from the viewpoint of protecting the inverter circuit. However, since the heat generation of the motor increases and many other components such as a contactor are required between the inverter and the motor, the system cost increases. In addition, when taking countermeasures on the motor side, the cost also increases because it is necessary to upgrade the grade of the magnet or increase the motor size.

[0005] The present invention has been made in view of such circumstances, and an object thereof is to provide a vehicle control unit and a traveling body that can effectively prevent damage to the inverter circuit during traveling on a slope when the electric motor of an electric two-wheeler is off.

Means for Solving the Problems

[0006] In order to achieve such an object, the technical means according to the present invention is a vehicle control unit that at least includes the following configuration.

[0007] A vehicle control unit connected to a first power source via a contactor, the vehicle control unit comprising: an inverter circuit for driving an alternating current electric motor; a power source for the inverter circuit for supplying power to the inverter circuit; a control unit for outputting a control signal for controlling the rotation of the electric motor to the inverter circuit; and an internal power source circuit having an enable terminal to which an input terminal of the inverter circuit is connected, wherein the inverter circuit is configured such that an arm for one phase of alternating current is constituted by a series circuit of an upper stage switching element and a lower stage switching element, and a freewheel diode connected in parallel to each switching element with the direction from the lower stage to the upper stage being the forward direction, and the vehicle control unit is configured such that a voltage induced when the electric motor rotates at a predetermined speed or more in an open state of the contactor activates the internal power source circuit, and when the internal power source circuit is activated in an open state of the contactor, the control unit activates the power source for the inverter circuit and outputs a command signal for turning on the lower stage switching elements of all the arms of a plurality of phases in the inverter circuit.

[0008] Further, in order to achieve the above object, a technical means according to the present invention is a traveling body having at least the following configuration.

[0009] A moving body equipped with a vehicle control unit connected to a first power source via a contactor, wherein the vehicle control unit includes an inverter circuit for driving an AC electric motor, a power source for the inverter circuit for supplying power to the inverter circuit, a control unit for outputting a control signal for controlling the rotation of the electric motor to the inverter circuit, and an internal power source circuit having an enable terminal to which the input terminal of the inverter circuit is connected. The inverter circuit is configured such that an arm for one phase of AC is constituted by a series circuit of an upper-stage switching element and a lower-stage switching element, and a freewheel diode connected in parallel to each switching element with the direction from the lower stage to the upper stage being the forward direction. The vehicle control unit is configured such that when the electric motor rotates at a predetermined speed or more in the open state of the contactor, the induced voltage activates the internal power source circuit. When the internal power source circuit is activated in the open state of the contactor, the control unit activates the power source for the inverter circuit and outputs a command signal for turning on the lower-stage switching elements of all the arms of the plurality of phases in the inverter circuit.

Advantages of the Invention

[0010] By having such characteristics, according to the present invention, it is possible to effectively prevent damage to the inverter circuit during traveling on a slope when the electric motor of the electric two-wheeler is in the off state.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Modes for Carrying Out the Invention

[0012] Hereinafter, an example of an embodiment of the vehicle control unit according to the present invention will be described with reference to the drawings. However, the following drawings are created for the purpose of explanation, and in some cases, members unnecessary for the explanation may not be intentionally illustrated. Also, for the purpose of explanation, members may be intentionally illustrated larger or smaller, and the drawings do not show the exact scale. In the following description, the same reference numerals in different drawings indicate parts having the same function, and duplicate explanations in each drawing are omitted as appropriate.

[0013] <Embodiment> (System Configuration) FIG. 1 is a system configuration diagram of a vehicle control unit according to an embodiment of the present invention. In the present embodiment, the vehicle control unit 1 controls and drives a motor 3 mounted near the rear wheel of an electric two-wheeler. In the embodiment of the present invention, a first power source 2 as a motor drive power source, which is a 96V lithium-ion battery, and a second power source 4 as a unit control power source, which is a 12V lead battery, are connected to the vehicle control unit 1.

[0014] The vehicle control unit 1 includes a series regulator 11 as an internal power supply circuit, a control unit 12 that generates, for example, a PWM signal or the like to drive and control the motor 3, an inverter circuit 13 including six power transistors as switching elements for driving the motor 3, and a power supply 14 for the inverter circuit.

[0015] The output from the main switch or key switch 16 is connected to the enable terminal of the series regulator 11. When the main switch or key switch is operated, a constant voltage of about 5V is applied to the enable terminal, and the series regulator 11 is activated. Also, the first power source 2 via the contactor 21 is connected to the enable terminal of the series regulator 11 after being divided in voltage. This voltage division ratio is set assuming the influence of the DC link capacitor so as to be an appropriate voltage value for activating the series regulator 11 by the induced voltage generated from the motor 3 during starting on a slope, which will be described later.

[0016] The control unit 12 receives signals from the main switch or key switch 16 and the throttle 17 provided on the handlebar of the electric two-wheeler. The control unit 12 generates, for example, a PWM signal for driving the circuits for normal motor control and charging control in response to the operations applied to the throttle 17 and the operations applied to a brake (not shown). In addition to this, the control unit 12 also performs circuit protection control, which will be described later.

[0017] The inverter circuit 13 has six power transistors as switching elements and a current detection resistor (not shown), and supplies a predetermined drive current to the motor 3 based on, for example, a PWM control signal from the control unit 12. Here, the six power transistors are MOSFETs. Although some of the notations by lead wires are omitted, three MOSFETs, namely, the upper U-phase FET 131U, the upper V-phase FET 131V, and the upper W-phase FET 131W, which are connected to the first power source 2 via the contactor 21, are arranged in the upper part shown in the figure. Three MOSFETs, namely, the lower U-phase FET 132U, the lower V-phase FET 132V, and the lower W-phase FET 132W, are arranged in the lower part shown in the figure. The source of the upper U-phase FET 131U is connected to the drain of the lower U-phase FET 132U, the source of the upper V-phase FET 131V is connected to the drain of the lower V-phase FET 132V, and the source of the upper W-phase FET 131W is connected to the drain of the lower W-phase FET 132W. Drive current is supplied from each of these connection nodes to the U-phase, V-phase, and W-phase of the motor 3.

[0018] Each power transistor is provided with a freewheel diode between the source and the drain with the direction from the lower side to the upper side defined as the forward direction in order to prevent the influence of the back electromotive force generated at the time of current interruption by continuing to conduct current even after turning off the switch. As the freewheel diode, a fast recovery diode with measures taken to reduce the reverse recovery time is used here.

[0019] The inverter circuit 13 has a power supply 14 for the inverter circuit so that the inverter circuit 13 can operate even when the contactor 21 is in the open state. Although the wiring is not shown, the power supply 14 for the inverter circuit is configured to be supplied with power from the second power supply 4. The power supply 14 for the inverter circuit is activated by a signal from the control unit 12.

[0020] The control unit 12 of the vehicle control unit 1 also outputs a signal to the battery management system 15. The battery management system 15 performs thermal control of the first power supply 2, detects an abnormal state due to overcurrent, and outputs a signal to the contactor 21 to cut off the vehicle control unit 1 and the first power supply 2. In addition, the battery management system 15 also performs monitoring and prediction calculations of voltage, current, temperature, SOC, etc.

[0021] In order to use the battery safely and effectively and to prevent damage to electronic devices, the vehicle control unit 1 performs important functions. For example, in order to reduce the power consumption of an electric two-wheeler, when a driver tries to turn off the main switch of the electric two-wheeler once while the electric two-wheeler is running on a slope to eliminate power consumption, the battery management system 15, when the main switch is turned off and the vehicle speed is above a certain level, does not immediately turn off the vehicle control unit 1, but cancels the back electromotive force by PWM control to prevent breakdown of the withstand voltage of the circuit device. This can be called circuit protection control during slope driving. However, this circuit protection control during slope driving is possible because the vehicle control unit 1 is operating. When the vehicle control unit 1 is not activated, breakdown of the withstand voltage of the device cannot be prevented. It is possible for the electric two-wheeler to run with the vehicle control unit 1 not activated. This is the case when starting on a slope where the driver starts the electric two-wheeler with the main switch of the electric two-wheeler stopped on a slope turned off. The vehicle control unit according to the embodiment of the present invention can effectively prevent breakdown of the withstand voltage of the device even in such a situation. This will be described below.

[0022] (Operation Sequence) While showing FIG. 1, the operation sequence of the vehicle control unit according to an embodiment of the present invention will be described. When the vehicle control unit 1 to which the first power source 2 and the second power source 4 are connected is in the system-off state, the contactor 21 is in the open state, and the 5V output of the series regulator 11 is off. The series regulator 11 starts its output by voltage input to the enable terminal. When the contactor is closed by the operation of the driver's key switch or main switch, and the voltage of the second power source 4 is input to the enable terminal, the series regulator 11 is activated. This operation is the startup operation of the series regulator 11 in normal times and is a normal startup.

[0023] Next, the startup at the start on a slope, which is a feature of the present invention, that is, the emergency startup, will be described. When starting to ride an electric two-wheeler so as to go down a slope by its own weight without operating the key switch or main switch of the electric two-wheeler, the motor 3 mounted near the rear wheel of the electric two-wheeler will be forcibly rotated. Then, a change occurs in the magnetic flux passing through the coil of the motor 3, and an induced voltage is generated. When the motor induced voltage is generated, a voltage is applied to the enable terminal of the series regulator 11 through the fast recovery diodes provided in each of the upper U-phase FET 131U, upper V-phase FET 131V, and upper W-phase FET 131W of the inverter circuit 13. For example, the voltage division ratio of the voltage division resistors is adjusted so that a voltage sufficient for the series regulator 11 to start is applied to the enable terminal when a voltage equal to or higher than a certain induced voltage, such as 30Vpeak at 3000 rpm, is generated.

[0024] More specifically, the voltage division ratio is adjusted so that the voltage applied to the series regulator 11 is the same during normal startup and emergency startup. In other words, the voltage division ratio is adjusted so that the induced voltage when starting the series regulator 11 is below the voltage of the driving power source. The value of this applied voltage corresponds to the induced voltage of 30Vpeak at 3000 rpm described above.

[0025] When the motor 3 rotates and about 4V is input to the enable terminal, the series regulator 11 is activated, and the control unit 12 is also activated. After that, the control unit 12 continues to operate with the power from the second power source 4. However, during the continuous operation, the control unit 12 disconnects the supply line from the motor so as not to exceed the withstand voltage of the enable terminal of the series regulator 11.

[0026] The fact that the control unit 12 is activated by a method other than normal input is determined by the state of the contactor 21, the voltage monitor value of the first power source 2, the rotational speed of the motor, etc. That is, it becomes possible to determine that it is an emergency start. The control unit 12 that determines that it is an emergency start activates the inverter circuit power supply 14.

[0027] When the inverter circuit power supply 14 is activated, the vehicle control unit 1 starts a control operation by PWM control. As a countermeasure against device withstand voltage breakdown, the vehicle control unit 1 turns on all of the lower U-phase FET 132U, the lower V-phase FET 132V, and the lower W-phase FET 132W to perform active short circuit control for fail-safe. By flowing a current using the lower power transistor by this control, it is possible to control so as not to exceed the element withstand voltage, that is, it is possible to control so that a failure of the inverter circuit 13 does not occur due to the induced voltage from the motor 3. Further, the vehicle control unit 1 prohibits torque control by throttle operation performed in normal operation. Specifically, the control unit 12 invalidates the throttle input.

[0028] Regarding the operation sequence described above, it will be described as the sequence of each system. FIG. 2 is an explanatory diagram showing the operation sequence of the vehicle control unit according to the embodiment of the present invention, and shows the vehicle state, the actions that occur, and the actions in the control unit side by arranging them side by side.

[0029] As for the vehicle state, first, the steering wheel is not locked and it will start from the state where the main switch is off. Since the driver is about to get out of the vehicle, naturally, the steering wheel lock is released. However, the driver will start the electric two-wheeler while keeping the main switch of the electric two-wheeler stopped on a slope turned off so as not to consume power.

[0030] When the rear wheel of the electric two-wheeler rotates, eventually, the motor 3 will be forced to rotate at a predetermined number or more such as 3000 rpm.

[0031] When the rotor of the motor rotates, the magnetic field of the magnet attached to the rotor causes electromagnetic induction with respect to the stator winding of the motor. An induced voltage is generated by the induced current generated by this action and is applied to the vehicle control unit 1. This induced voltage is basically a sine wave and is smoothed by the DC link capacitor through the freewheel diodes of the upper U-phase FET 131U, upper V-phase FET 131V, and upper W-phase FET 131W of the inverter circuit 13. This smoothed voltage is applied to the enable terminal of the series regulator 11. Upon receiving the enable command, the series regulator 11 is supplied with the power of the 12V second power source as the main power source. Next, after the control unit 12 executes the same processing as the initial target diagnosis processing executed at normal startup, it starts up, and the vehicle control unit 1 is turned on. The vehicle control unit 1 determines that it is an emergency startup by checking that the contactor 21 is open, etc.

[0032] The vehicle control unit 1 that has determined that it is an emergency startup activates the power supply 14 for the inverter circuit. When the power supply 14 for the inverter circuit is activated, smart authentication is executed to confirm whether the driver has a legitimate key.

[0033] Thereafter, the vehicle control unit 1 executes PWM control necessary for protecting the inverter circuit 13. Specifically, the vehicle control unit 1 turns on all of the lower U-phase FET 132U, the lower V-phase FET 132V, and the lower W-phase FET 132W to perform active short circuit control for fail-safe. By flowing current using the lower power transistors through this control, it is possible to control so as not to exceed the element breakdown voltage, that is, it is possible to control so that a failure of the inverter circuit 13 does not occur due to the induced voltage from the motor 3. Also, the vehicle control unit 1 prohibits torque control by throttle operation performed during normal operation. In addition, the control unit 12 of the vehicle control unit 1 stops some functions such as failure detection. On the other hand, the control unit 12 performs display control indicating that it is in the correction mode.

[0034] In this embodiment, every 5 seconds, the motor speed is monitored, and the PWM control for circuit protection is continued until it becomes zero. If the speed becomes zero, the vehicle control unit 1 sends a command signal to stop the inverter circuit power supply 14. Before that, if the main switch is turned on, such monitoring is not performed because it shifts to the normal state.

[0035] As circuit protection control, it is also conceivable to start the series regulator 11 and the control unit 12 at the time of emergency start, and the control unit 12 that has determined that it is an emergency start operates the entire system by closing the contactor 21. However, in that case, it is necessary to sufficiently ensure consistency throughout the system, and it will be costly in terms of design changes. The vehicle control unit according to the embodiment of the present invention can utilize the conventional system with only minimal modifications by providing the inverter circuit power supply 14 to which the power of the second power supply is supplied.

[0036] As described above, the vehicle control unit according to the embodiment of the present invention and the traveling body equipped with the vehicle control unit have been described in detail. However, the specific configuration is not limited to these embodiments, and design changes and the like within the scope not departing from the gist of the present invention are also included in the present invention. For example, as the circuit board, the internal power supply circuit has been described by way of example of a series regulator, but the internal power supply circuit may be configured by a DC-DC converter. Further, although the traveling body as the object has been described as an electric two-wheeler, it can also be applied to electric three-wheelers such as electric three-wheel bikes with two front wheels or commercial electric scooters for delivery with two rear wheels. For the type with two rear wheels, two motors may be provided. As described in this specification, in a situation where the system is not activated, by utilizing the induced voltage from the motor to activate the system and then performing subsequent circuit protection processing, that is, without arranging particularly different hardware elements or the like compared to the conventional system, the characteristic configuration capable of achieving effective circuit protection should be correctly recognized.

Explanation of Signs

[0037] 1 Vehicle control unit 11 Series regulator (internal power supply circuit) 12 Control unit 13 Inverter circuit 131U Upper U-phase FET 131V Upper V-phase FET 131W Upper W-phase FET 132U Lower U-phase FET 132V Lower V-phase FET 132W Lower W-phase FET 15 Battery management system 16 Main switch, key switch 17 Throttle 2 First power supply 21 Contactor 3 Motor 4 Second power supply

Claims

1. A vehicle control unit connected to a first power source via a contactor, wherein the vehicle control unit includes: an inverter circuit for driving an AC electric motor; a power source for the inverter circuit for supplying power to the inverter circuit; a control unit that outputs a control signal for controlling the rotation of the electric motor to the inverter circuit; an internal power source circuit having an enable terminal to which an input terminal of the inverter circuit is connected; and the inverter circuit includes an arm for one phase of AC configured by a series circuit of an upper-stage switching element and a lower-stage switching element, and a freewheel diode connected in parallel to each switching element with the direction from the lower stage to the upper stage being defined as the forward direction; wherein the vehicle control unit is configured such that: when the electric motor rotates at a predetermined speed or higher in an open state of the contactor, a voltage induced is used to activate the internal power source circuit; when the internal power source circuit is activated in an open state of the contactor, the control unit activates the power source for the inverter circuit and outputs a command signal to turn on the lower-stage switching elements of all the arms of the plurality of phases in the inverter circuit. A vehicle control unit characterized by the above.

2. The vehicle control unit is configured such that: when the internal power source circuit is activated in an open state of the contactor, a part of the initial target diagnostic process executed during normal startup is omitted, and the control unit is activated. The vehicle control unit according to claim 1, characterized by the above.

3. The vehicle control unit further includes a second power source, and when the internal power source circuit is activated in an open state of the contactor, the initial target diagnostic process executed during normal startup is executed, and the control unit is activated. The vehicle control unit according to claim 1, characterized by the above.

4. When the internal power source circuit is activated in an open state of the contactor, the control unit invalidates the input from the throttle. The vehicle control unit according to claim 1, characterized by the above.

5. A traveling body comprising the vehicle control unit according to any one of claims 1 to 4. Characterized by the above.

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