JP5576722B2 - Overvoltage suppressing device and motor driving device - Google Patents

Description

  INDUSTRIAL APPLICABILITY The present invention is used in industrial equipment or electric vehicles such as electric assist bicycles, electric motorcycles, and electric vehicles, and suppresses overvoltage caused by regenerative power when performing motor drive control while performing power regeneration on a battery. The present invention relates to a device and a motor drive device.

  Conventionally, when the load that can absorb regenerative power during motor regeneration is small, the voltage of the power supply line rises. For example, in an electric vehicle such as an electric assist bicycle, an electric motorcycle, and an electric vehicle, regenerative electric power when the motor is decelerated is returned to the battery to extend the cruising distance (see, for example, Patent Document 1). When the regenerative power is returned in the fully charged state, the regenerative current loses a path for flowing, and the power supply voltage rises. As a result, the voltage applied to the switching element of the drive device (inverter) also increases, and there is a possibility that an overvoltage state may occur with respect to the switching element.

FIG. 18 is a schematic explanatory diagram of a motor drive device including a conventional inverter circuit.
As shown in FIG. 18A, the inverter circuit is a PWM inverter based on pulse width modulation (PWM) including a bridge circuit 6A in which six switching transistors are bridge-connected and a smoothing capacitor 6B.

More specifically, the bridge circuit 6A of the inverter circuit 6 includes a high potential side U-phase transistor 6UH, a low potential side U phase transistor 6UL, a high potential side V phase transistor 6VH, and a low potential side V phase that are paired for each phase. The transistor 6VL, the high potential side W phase transistor 6WH, and the low potential side W phase transistor 6WL are bridge-connected. The transistors 6UH, 6UL, 6VH, 6VL, 6WH, and 6WL are turned on / off by a PWM drive signal from the drive circuit 4.
As shown in FIG. 18B, the rotational speed RM of the motor 10 is constant until time t1. At this time, in order to drive the motor 10, the current IB of the battery E and the voltage VB of the battery E are also substantially constant (positive side: operating as a power source).
Then, if the accelerator is turned off at time t1, the rotational speed RM of the motor gradually decreases. As a result, the motor 10 enters a regenerative operation, and the current IB of the battery E gradually increases as the regenerative current increases. (Negative side: charging operation).

By the charging operation based on the regenerative operation, the voltage VB of the battery E gradually increases. However, at the time when the motor stops and the regenerative operation also stops (time t2 or time t12), FIG. As shown in FIG. 18, when the battery is fully charged, the voltage of the battery VB is naturally higher than that when the battery capacity is reduced as shown in FIG.
In order to cope with this, it is conceivable to increase the breakdown voltage of components such as switching elements, but this leads to an increase in cost and an increase in internal resistance.
In addition, the battery may be charged at a rated voltage or higher to generate heat.

Japanese Patent Laid-Open No. 2004-120841

FIG. 19 is a schematic explanatory diagram of a motor drive device including another conventional inverter circuit.
As a solution technique that avoids the above points and does not affect the driving device, as shown in FIG. 19A, on the lines (U-phase line, V-phase line, W-phase line) connecting the motor and the driving device. A method has been proposed in which switches SW1 to SW3 are provided to forcibly cut off these lines.
According to this method, at time t21, the regenerative power line is also cut off, and as shown in FIG. 19B, the current IB of the battery E becomes 0, and the battery voltage VB does not increase. From the time t21 to the time t22, the motor continues to rotate with inertia, becomes a non-control state, becomes a so-called torque loss state, and causes a problem of increasing the braking distance and increasing the cost of the circuit breaker.
FIG. 20 is a schematic explanatory diagram of a motor driving device provided with still another conventional inverter circuit.

  As another method, as shown in FIG. 20A, a circuit breaker or a switch SW4 such as a semiconductor switch is attached to the power line between the battery and the control device, and when the battery is fully charged, the regenerative current is supplied to the battery. Although it is possible to cut off from the flowing path, as shown in FIG. 20B, since the battery current IB becomes 0 at time t31, the battery E is protected from overvoltage, and the battery voltage VB is constant. However, it is necessary to increase the breakdown voltage of the switching element, etc., leading to an increase in cost and an increase in internal resistance. Further, the voltage VP on the control circuit side including the bridge circuit 6A side continues to increase until the rotation of the motor 10 is stopped until the time t32 is reached, so that the switching on the control circuit side including the bridge circuit 6A side is performed. It is necessary to increase the breakdown voltage of the element, which leads to an increase in cost and an increase in internal resistance.

FIG. 21 is a schematic explanatory diagram of a motor drive device provided with still another conventional inverter circuit.
In order to solve this, as shown in FIG. 21A, a resistor R and a transistor Tr as a switch are attached between the power supplies, and when the voltage of the power supply line rises, the transistor Tr as a switch is turned on, and the resistance R There is a method of suppressing the voltage rise by pouring and using regenerative power.
However, it is conceivable that an increase in size due to the incorporation of a resistor R having a value sufficient to consume regenerative power in the apparatus or an effect due to heat generation.

For example, in Patent Document 1, in the invention of an electric vehicle, a method of changing the frequency of switching (for example, on-duty) according to the voltage of the overhead line is used while using a method of consuming regenerative power by resistance. There arises a problem that the effect of size increase and heat generation due to the incorporation of a resistor having a capacity capable of consuming regenerative power into the apparatus arises.
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an overvoltage suppressing device and a motor driving device having the overvoltage suppressing device capable of suppressing the voltage increase of the battery or the control device due to the regenerative power of the motor without adding components. There is.

In order to achieve the above object, according to a first aspect of the present invention, there is provided a detector for detecting a regenerative voltage in an overvoltage suppressing device for suppressing an overvoltage in a motor driving device that regenerates electric power generated by a motor to a battery, and a detection The regenerative voltage is compared with the battery and a voltage threshold value of the battery, which is a voltage for starting an operation of suppressing an overvoltage by suppressing a voltage increase in the motor and the motor drive device. When the voltage threshold is exceeded, the motor current is increased in a direction opposite to the power running direction so as to decrease the battery current increased with an increase in regenerative current and to keep the battery voltage at a constant value. And a drive control circuit for driving.
According to the above configuration, the detector detects the regenerative voltage. As a result, the drive control circuit compares the detected regenerative voltage with the voltage threshold of the battery, and when the regenerative voltage exceeds the voltage threshold, it drives the motor in the opposite direction to the power running direction. To do.
Therefore, when the regenerative voltage exceeds the voltage threshold value, the regenerative voltage is used to drive in the direction opposite to the power running direction, and the increase in the voltage of the battery or the control device due to the regenerative power of the motor can be suppressed. .

According to a second aspect of the present invention, in the first aspect, the motor and the battery are a power motor and a battery mounted on a vehicle, and the electric power regenerative brake is generated by regenerating the electric power of the motor to the battery. It is made to function.
According to the above configuration, the electric power of the motor is regenerated to the battery to function as an electric power regenerative brake, and the electric power can be effectively used, and the battery or control device voltage increase due to the regenerative electric power of the motor can be suppressed. The burden on the control device can be reduced and the reliability can be improved.

According to a third aspect of the present invention, in the first or second aspect, the voltage threshold value of the battery is set as an overcharge prevention determination value for preventing overcharge of the battery. .
According to the above configuration, when the regenerative voltage exceeds the overcharge prevention determination value that prevents the battery from being overcharged, the regenerative voltage is used to drive in the direction opposite to the power running direction, An increase in voltage of the battery or the control device due to regenerative power can be suppressed.

According to a fourth aspect of the present invention, there is provided a motor drive device that performs drive control of a motor, a battery that supplies power to the motor, a detector that detects a regenerative voltage, the detected regenerative voltage, the battery, and a motor drive. When the regenerative voltage exceeds the voltage threshold value, the regenerative current is compared with the voltage threshold value of the battery, which is a voltage for starting the operation of suppressing the overvoltage by suppressing the voltage rise in the device. And a drive control circuit for driving the motor in a direction opposite to the power running direction so as to reduce the battery current increased with the increase in voltage and to keep the voltage of the battery at a constant value. Features.
According to the above configuration, the detector detects the regenerative voltage when the motor is driven by supplying power from the battery.

As a result, the drive control circuit compares the detected regenerative voltage with the voltage threshold value of the battery, and when the regenerative voltage is less than the voltage threshold value, the power generated by the motor is supplied to the battery. When the regenerative voltage exceeds the voltage threshold, the motor is driven in the direction opposite to the power running direction.
Therefore, when the regenerative voltage is less than the voltage threshold, the battery is charged with regenerative power, and when the regenerative voltage exceeds the voltage threshold, the regenerative voltage is reversed with respect to the power running direction. It is used for driving in the direction, and the voltage rise of the battery or the control device due to the regenerative power of the motor can be suppressed.

  According to the present invention, there is an effect that it is possible to suppress an increase in the voltage of the battery or the control device due to the regenerative power of the motor without causing the addition of parts.

It is operation | movement principle explanatory drawing of the motor drive system which concerns on this embodiment. It is a figure showing typically composition of a motor drive system concerning an embodiment. It is a lineblock diagram showing the motor concerning this embodiment. It is a top view which shows the structure of a rotor. It is a top view which shows the structure of a stator. It is a figure which shows the structure of a drive circuit with a magnetic detection circuit. It is a figure which shows the structure of another drive circuit with a magnetic detection circuit. It is a block diagram which shows the motor control system of a motor drive system. It is a voltage waveform at the time of power running (during motor drive) of the embodiment. It is a voltage waveform at the time of regeneration of an embodiment. It is a voltage waveform at the time of overvoltage suppression (reverse rotation) of embodiment. It is a current waveform at the time of overvoltage suppression (during reverse rotation) of the embodiment. It is a change state explanatory view of battery current and battery voltage. It is operation | movement outline explanatory drawing. It is explanatory drawing of an operation control map. It is a block diagram which shows the motor control system of a modification. It is a block diagram which shows the motor control system of another modification. It is outline | summary explanatory drawing of the motor drive device provided with the conventional inverter circuit. It is outline | summary explanatory drawing of the motor drive device provided with the other conventional inverter circuit. It is outline | summary explanatory drawing of the motor drive device provided with the further another inverter circuit of the past. It is outline | summary explanatory drawing of the motor drive device provided with the further another inverter circuit of the past.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings, taking as an example a case where an electric motor used in an electric vehicle is a DC brushless motor. In the following description, the DC brushless motor is simply referred to as a motor.
FIG. 1 is an explanatory diagram of the operation principle of the motor drive system according to the present embodiment.
As shown in FIG. 1, the motor drive system 1 controls a DC power source E such as an in-vehicle battery, a motor 10 that is driven by electric power of the DC power source E, and a power source for driving the vehicle, and driving of the motor 10. And a control device 2 for performing the operation.
The control device 2 controls the waveform of the motor drive current based on the command speed that is the command value of the rotation speed of the motor 10, and the DC current of the DC power supply E is controlled under the control of the drive circuit 4. And an inverter circuit 6 that converts the current into a motor drive current and outputs it to the motor 10.

The drive circuit 4 includes a battery current detection circuit 4A that detects a current flowing through the battery E, a battery voltage detection circuit 4B that detects a terminal voltage of the battery E, an inverter voltage detection circuit 4C that detects a voltage of the inverter circuit 6, It has.
The inverter circuit 6 is a PWM inverter by pulse width modulation (PWM) including a bridge circuit 6A in which six switching transistors are bridge-connected and a smoothing capacitor 6B.

  More specifically, the bridge circuit 6A of the inverter circuit 6 includes a high potential side U-phase transistor 6UH, a low potential side U phase transistor 6UL, a high potential side V phase transistor 6VH, and a low potential side V phase that are paired for each phase. The transistor 6VL, the high potential side W phase transistor 6WH, and the low potential side W phase transistor 6WL are bridge-connected. The transistors 6UH, 6UL, 6VH, 6VL, 6WH, and 6WL are turned on / off by PWM drive signals UP, SUL, SVH, SVL, SWH, and SWL from the drive circuit 4. As each of the transistors 6UH, 6UL, 6VH, 6VL, 6WH, and 6WL, a switching transistor (switching element) such as an IGBT or a MOSFET can be used.

  Here, the high potential side U-phase transistor 6UH, the high potential side V phase transistor 6VH, and the high potential side W phase transistor 6WH are connected to the high potential side to form a high side arm, and the low potential side U phase transistor 6UL, The low potential side V-phase transistor 6VL and the low potential side W phase transistor 6WL are connected to the low potential side to form a low side arm.

Further, the high potential side U phase transistor 6UH, the low potential side U phase transistor 6UL, the high potential side V phase transistor 6VH, the low potential side V phase transistor 6VL, the high potential side W phase transistor 6WH, and the low potential side W phase transistor 6WL Free wheel diodes 7UH, 7UL, 7VH, 7VL, 7WH, and 7WL are connected between the collector and the emitter so as to be in the forward direction from the emitter to the collector.
In the above configuration, when the motor 10 is driven, the detection voltage of the battery voltage detection circuit 4B is within the specified voltage range, and the detection voltage of the inverter voltage detection circuit 4C is also within the specified voltage range for driving the motor 10. The motor 10 is rotationally driven as usual.

On the other hand, when the motor 10 is decelerated, regenerative electric power is generated in the motor 10, and this regenerative electric power flows through the free wheel diode 7WL, through the motor 10, and passes through the free wheel diode 7UH, for example. It flows into the battery E.
At this time, if the detection voltage of the battery voltage detection circuit 4B is within the specified voltage range and is equal to or higher than the voltage of the battery E at that time, the battery E is charged.
When the detection voltage of the battery voltage detection circuit 4B exceeds the specified voltage, the motor 10 is driven to rotate in the direction opposite to the normal direction, the regenerative power is consumed by the motor 10, and the voltage or control of the battery E is controlled. The voltage of the device 2 does not increase.
Therefore, it is possible to suppress an increase in the voltage of the battery or the control device due to the regenerative power of the motor without incurring additional parts.

FIG. 2 is a diagram schematically illustrating a configuration of the motor drive system according to the embodiment.
In FIG. 2, the same parts as those in FIG.
As shown in FIG. 2, the motor drive system 1 controls a DC power source E such as an in-vehicle battery, a motor 10 that is driven by electric power of the DC power source E, and a power source for driving the vehicle, and driving of the motor 10. And a control device 2 for performing the operation. The control device 2 controls the waveform of the motor drive current based on the command speed that is the command value of the rotation speed of the motor 10, and the DC current of the DC power supply E is controlled under the control of the drive circuit 4. And an inverter circuit 6 that converts the current into a motor drive current and outputs it to the motor 10. The inverter circuit 6 includes a high potential side U-phase transistor 6UH, a low potential side U phase transistor 6UL, a high potential side V phase transistor 6VH, a low potential side V phase transistor 6VL, a high potential side W phase transistor 6WH, and a low potential side W phase. This circuit is a combination of transistors 6WL, and includes a high potential side U phase transistor 6UH, a low potential side U phase transistor 6UL, a high potential side V phase transistor 6VH, a low potential side V phase transistor 6VL, a high potential side W phase transistor 6WH, a low The potential-side W-phase transistor 6WL is turned on / off by a PWM drive signal from the drive circuit 4. The command speed is generated by a computer on the vehicle side and input to the drive circuit 4 of the control device 2.

FIG. 3 is a configuration diagram illustrating the motor according to the present embodiment.
As shown in FIG. 3, the motor 10 is an inner rotor type motor 10 having a rotor 12 and a stator 14.
The rotor 12 includes a cylindrical casing 16 and a rotor shaft 18 that extends in the axial direction at the center of the casing 16. As shown in FIG. 3, a permanent magnet 20 is disposed inside the housing 16 along the inner wall of the housing 16, and is configured as an 8-pole (4-pole pair) motor 10, for example.
FIG. 4 is a plan view showing the configuration of the rotor.
A detection magnet 22 is installed in a portion of the rotor 12 that faces the stator 14. The permanent magnet 20 is installed for rotating the rotor 12, and the detection magnet 22 is installed for detecting the speed of the rotor 12.

  The detection magnet 22 is magnetized by alternately arranging N poles and S poles so as to correspond to the magnetic pole positions of the motor 10. Therefore, the detection magnet 22 has eight boundaries (the first boundary 24a to the eighth boundary 24h) with respect to the boundary between the N pole and the S pole.

FIG. 5 is a plan view showing the configuration of the stator.
On the other hand, as shown in FIG. 5, the stator 14 has twelve slots (first slot 26a to twelfth slot 261) at equal intervals along the circumference and, for example, in the clockwise direction, the first slot 26a and the second slot. The second slot 26b, the third slot 26c,... Are arranged in this order. Among them, the first slot 26a, the fourth slot 26d, the seventh slot 26g, and the tenth slot 26j are wound with the first phase winding, and the second slot 26b, the fifth slot 26e, the eighth slot 26h, and the A second phase winding is wound around the 11th slot 26k, and a third phase winding is wound around the third slot 26c, the sixth slot 26f, the ninth slot 26i and the twelfth slot 26l. In FIG. 4, the first phase winding is indicated by [1], the second phase winding is indicated by [2], and the third phase winding is indicated by [3].

  Further, the stator 14 is provided with a hole 28 into which the end of the rotor shaft 18 is inserted at the center thereof, and a mounting plate having a U-shape, for example, is formed so as to surround the hole 28 around the hole 28. 30 is installed. Further, around the hole 28, there are a first connection terminal portion 32a for the first phase winding, a second connection terminal portion 32b for the second phase winding, and a third connection for the third phase winding. A connection terminal portion 32c is provided.

Six magnetic sensors (first magnetic sensor 34 a to sixth magnetic sensor 34 f) are arranged on the surface (for example, the upper surface) of the mounting plate 30 facing the detection magnet 22 of the rotor 12.
Specifically, when the reference line m passing through the center position of the hole portion 28 and passing through the centers of the fifth slot 26e and the eleventh slot 26k is considered, the upper surface of the mounting plate 30 is on the reference line m. In addition, the first magnetic sensor 34a is installed at a position on the fifth slot 26e side, and the first magnetic sensor 34a is spaced from the first magnetic sensor 34a along the circumference of the hole 28 by, for example, 30 ° clockwise. The second magnetic sensor 34b is installed, and the third magnetic sensor 34c is installed at a position 30 ° away from the second magnetic sensor 34b along the circumference of the hole 28.
Similarly, the fourth magnetic sensor 34d is installed on the reference line m on the upper surface of the mounting plate 30 and on the eleventh slot 26k side, and the circle of the hole 28 is formed from the fourth magnetic sensor 34d. For example, a fifth magnetic sensor 34e is installed at a position spaced 30 ° in the counterclockwise direction along the circumference, and a sixth magnetic sensor is disposed at a position spaced 30 ° along the circumference of the hole 28 from the fifth magnetic sensor 34e. 34f is installed.
Note that the number and position of the magnetic sensors described above may be changed as appropriate according to the number of slots. For example, when the number of slots is SL, the magnetic sensor is
360 ° / S [°]
It is necessary to install every time. Furthermore, when magnetic sensors for detecting the magnetic pole positions are arranged in the U phase, the V phase, and the W phase, it is preferable that the following equation is satisfied when the number of magnetic poles is NM.
(360 ° / SL) × 2> 360 ° / NM> 360 ° / SL
This is because the switching of the position detection signal is clearly determined.

  Among the first magnetic sensor 34a to the sixth magnetic sensor 34f, the first magnetic sensor 34a to the third magnetic sensor 34c are for detecting the forward rotation speed of the rotor 12, and the first magnetic sensor 34a is the first magnetic sensor 34a. The second magnetic sensor 34b corresponds to the second phase, and the third magnetic sensor 34c corresponds to the third phase. Therefore, in other words, the first magnetic sensor 34a63 to the third magnetic sensor 34c are arranged in the order of the first magnetic sensor 34a, the second magnetic sensor 34b, and the third magnetic sensor 34c along the forward rotation direction of the rotor 12. And 30 ° apart from each other along the forward rotation direction of the rotor 12.

  Similarly, the fourth magnetic sensor 34d to the sixth magnetic sensor 34f are for detecting the reverse rotation speed of the rotor 12, the fourth magnetic sensor 34d corresponds to the first phase, and the fifth magnetic sensor 34e is the first one. Corresponding to the three phases, the sixth magnetic sensor 34f corresponds to the second phase. Therefore, in other words, the fourth magnetic sensor 34d to the sixth magnetic sensor 34f are arranged in the order of the fourth magnetic sensor 34d, the fifth magnetic sensor 34e, and the sixth magnetic sensor 34f along the reverse direction of the rotor 12. They are arranged and arranged 30 ° apart from each other along the reverse direction of the rotor 12.

  The first magnetic sensor 34a to the sixth magnetic sensor 34f are each configured by a Hall IC. The Hall IC is a magnetic sensor in which a Hall element and a logic circuit are integrated into an IC, and detects the magnetic pole (N pole or S pole) of the detection magnet 22 of the rotor 12 and the strength of the magnetic pole by the electromagnetic phenomenon of the Hall element. . Therefore, when the rotor 12 rotates, an analog voltage signal proportional to the magnetic flux density is output from the Hall element. The logic circuit shapes the analog voltage signal from the Hall element and outputs it as a digital waveform corresponding to the polarity of the magnetic field, for example, a high-level digital waveform at the N pole and a low-level digital waveform at the S pole. In the present embodiment, for example, an open collector output type Hall IC having an output transistor is used.

The first magnetic sensor 34a to the sixth magnetic sensor 34f are provided, and a magnetic detection circuit 52 for detecting the magnetic pole position of the motor 10 is configured as shown in FIG. As shown in FIGS. 1 and 6 (described later), the magnetic detection circuit 52 includes a first magnetic sensor 34a to a third magnetic sensor 34c for detecting the rotor position in the forward direction, and outputs a first digital waveform of three phases. And a second magnetic sensor unit 64b including a fourth magnetic sensor 34d to a sixth magnetic sensor 34f for detecting the rotor position in the reverse direction and outputting a three-phase second digital waveform. These first and second digital waveforms are input to the drive circuit 4 as magnetic pole position detection signals. Here, the first magnetic sensor 34a to the third magnetic sensor 34c and the fourth magnetic sensor 34d to the sixth magnetic sensor 34f are configured by Hall ICs.
As shown in FIG. 1, the drive circuit 4 includes a magnetic pole position detection signal processing circuit 54, a pulse generation circuit 56, and a CPU 58. The CPU 58 operates as at least the rotor position detecting means 60 and the rotor speed detecting means 62 by software.
In the above description, the Hall IC is used to detect the rotor position. However, if the rotational position can be detected, an encoder such as a rotary encoder or a resolver provided with a coil on the rotor shaft is used. Various methods such as a method of reading the positions of gear teeth formed on the shaft of the rotor are possible.

FIG. 6 is a diagram showing the configuration of the drive circuit together with the magnetic detection circuit.
In FIG. 6, the configuration for generating a signal input to the inverter circuit 6 is not shown.
As shown in FIG. 6, the magnetic pole position detection signal processing circuit 54 has a digital waveform from the magnetic detection circuit 52, that is, a three-phase first digital waveform from the first magnetic sensor unit 64a that detects the rotor position in the forward direction. A pull-up resistor 66 that stabilizes the three-phase second digital waveform from the second magnetic sensor unit 64b that detects the rotor position in the reverse direction, and a noise filter 68 (low-pass filter) that suppresses high-frequency components (noise). Based on a waveform shaping circuit 70 having a Schmitt trigger function and shaping a waveform rounded by the noise filter 68 into a pulse waveform, and a control signal Sc indicating normal rotation or reverse rotation of the rotor 12 from the CPU 58, three-phase The first digital waveform or the three-phase second digital waveform is switched and selected, and the three-phase rotor position detection pulse signal Sa (first phase A selection circuit 72 for outputting a rotor position detection pulse signal SA1 to SA3) of the third phase, and a.

  The pulse generation circuit 56 generates a rotor speed detection pulse signal Sb, which is a series of pulse signals in which the rising and falling edges of the three-phase rotor position detection pulse signals Sa1 to Sa3 from the selection circuit 72 are reflected. It is. That is, the pulse generation circuit 56 exclusively uses the first-phase rotor position detection pulse signal Sa1 and the second-phase rotor position detection pulse signal Sa2 among the three-phase rotor position detection pulse signals Sa from the selection circuit 72. A first logic circuit 74 that outputs a logical sum, and a second logic circuit that outputs an exclusive OR of the third-phase rotor position detection pulse signal Sa3 and the output of the first logic circuit 74 as the rotor speed detection pulse signal Sb. 76.

The rotor position detecting means 60 operating in the CPU 58 detects the rotational position of the rotor 12 based on the three-phase rotor position detection pulse signals Sa1 to Sa3 from the selection circuit 72, and the rotor speed detecting means 62 operating in the CPU 58 is Based on the rotor speed detection pulse signal Sb from the pulse generation circuit 56, the rotational speed (forward rotation speed or reverse rotation speed) of the rotor 12 is detected. In this case, the CPU 58 controls the rotational drive of the motor 10 based on the detected rotational speed so that the rotational speed indicated by the generated speed command value or the external speed command value is obtained. A configuration for this drive control will be described later.
Here, for example, in the case of detecting only the rotor position and the normal rotation speed during the normal rotation of the rotor 12, the second magnetic sensor unit 64b (the fourth magnetic sensor 34d to the sixth magnetic sensor 34f) relating to the reverse rotation of the rotor 12 is omitted. In accordance with this, some of the components of the pull-up resistor 66, the components of the noise filter 68, and the components of the waveform shaping circuit 70 can be omitted, and the selection circuit 72 can be omitted.

FIG. 7 is a diagram showing the configuration of another drive circuit together with the magnetic detection circuit.
Specifically, as shown in FIG. 7, the magnetic detection circuit 52 includes a first magnetic sensor 34 a to a third magnetic sensor 34 c that detect the rotor position in the forward direction, and outputs a three-phase digital waveform. 64c. Here, the 1st magnetic sensor 34a-the 3rd magnetic sensor 34c are comprised by Hall IC.
The magnetic pole position detection signal processing circuit 54 suppresses the high-frequency component (noise) and the pull-up resistor 66A that stabilizes the digital waveform from the magnetic detection circuit 52, that is, the three-phase digital waveform from the magnetic sensor unit 64c. A noise filter 68A (low-pass filter), a waveform shaping circuit 70A having a Schmitt trigger function and shaping a waveform distorted by the noise filter 68 into three-phase rotor position detection pulse signals Sa1 to Sa3 having a pulse waveform; It is equipped with.
The pulse generation circuit 56 generates a rotor speed detection pulse signal Sb that is a series of pulse signals in which the rising and falling edges of the three-phase rotor position detection pulse signals Sa1 to Sa3 from the waveform shaping circuit 70A are reflected. .

Next, the control system of the motor 10 will be described.
FIG. 8 is a block diagram showing a motor control system of the motor drive system.
This motor control system 100 receives a command speed ω _rm ^* from a computer mounted on a vehicle and inputs it to the control device 2 and performs feedback control so that the motor 10 is driven at the command speed ω _rm ^* .
That is, as shown in FIG. 8, the motor control system 100 includes a speed controller 90 that functions as a speed control unit, a duty map 91, an advance angle map 92, and a conduction angle extension map 95. A waveform generator 93 and a voltage type PWM inverter 96 functioning as a generation unit are provided, and the rotor position detection unit 60 and the rotor speed detection unit 62 described above are provided as a position / speed detection unit.
The functions as the speed control unit, the drive signal generation unit, and the position / speed detection unit described above are realized by the CPU 58 included in the drive circuit 4.

The CPU 58 functioning as a speed control unit calculates a voltage command value from a command speed ω _rm ^* input from a computer included in the vehicle and a rotational speed ω _rm detected by the position / speed detection unit, and a drive signal generation unit 86. Output to. More specifically, the speed control unit 84 includes a speed controller 90 that calculates a torque command value from the command speed ω _rm ^* and the rotational speed ω _rm, and a duty that can be searched by the torque command value and the command speed ω _rm ^* . (Duty) A map 91, an advance angle map 92, and an energization angle extension map 95 are provided.

The speed controller 90 has a proportional (P) controller and an integral (I) controller, and performs PI control (proportional / integral control) based on the deviation between the command speed ω _rm ^* and the rotational speed ω _rm. The torque command value is calculated by compensating for the error.
The duty map 91 is a map that preliminarily defines the relationship between the command speed ω _rm ^* , the duty of a PWM drive signal described later, and torque. By searching the duty map 91 using the torque command value and the command speed ω _rm ^* , the duty at which the torque of the torque command value is obtained is determined.

The advance angle map 92 is a map in which the relationship between the command speed ω _rm ^* , the advance angle, and the torque is defined in advance. That is, by searching the advance angle map 92 by the torque command value and the command speed omega _rm ^*, the optimum advance angle with respect to the torque command value and the command speed omega _rm ^* is obtained.
The energization angle extension map 95 is a map that preliminarily defines the relationship between the command speed ω _rm ^* and the energization angle, the energization angle extension amount, and the torque that are the reference in the motor 10. That is, to find the conduction angle extended map 95 by the torque command value and the command speed omega _rm ^*, the optimum conduction angle with respect to the torque command value and the command speed omega _rm ^* is obtained.
Then, a voltage command value including the indicated values of duty, advance angle, and energization angle is input to the waveform generator 93 of the drive signal generation unit.

Thus, the waveform generator 93, together with the magnetic pole position theta _re of the rotor 12 from the position and speed detecting section to be described later is input, the voltage command value is input from the speed control unit, the magnetic pole position theta _re and the voltage command value Based on the sine wave modulation signals Vua ^* , Vva ^* and Vwa ^*, and outputs them to the voltage type PWM inverter 96.

The voltage type PWM inverter 96 generates a PWM drive signal based on the sine wave modulation signals Vua ^* , Vva ^* , and Vwa ^* . Specifically, the voltage type PWM inverter 96 generates PWM drive signals Vua, Vva, and Vwa by a triangular wave comparison asynchronous method, and outputs them to the inverter circuit 6.
The CPU 58 functioning as a position / speed detector includes the rotor position detector 60 and the rotor speed detector 62 described above, and the position of the rotor 12 (ie, the magnetic pole position) θ _re and the rotational speed ω of the rotor 12. _rm is detected, the rotational speed ω _rm is output to the speed controller 84, and the magnetic pole position θ _re is output to the waveform generator 93.

Next, the operation of the embodiment will be described.
FIG. 9 is a voltage waveform during power running (during motor driving) in the embodiment.
When rotating the motor 10 in the power running direction (drive direction, direction for moving the vehicle), for example, in the case of the 120-degree energization method, as shown in FIG. 9, the PWM drive signals Vua, Vva, Vwa The phase of the high potential side U phase transistor 6UH, the high potential side V phase transistor 6VH, and the high potential side W phase transistor 6WH is shifted by 120 degrees, and the outputs of the first magnetic sensor 34a to the third magnetic sensor 34c that are Hall ICs Is turned on / off by PWM drive with PWM drive signals Vua, Vva, Vwa from the drive circuit 4 so that the ON period is located in the ON period, and the low potential side V-phase transistor 6VL, the low potential side The PWM drive signal V from the drive circuit 4 is shifted by 120 degrees for the W-phase transistor 6WL and the low-potential-side W-phase transistor 6WL. PWM drive is performed by a, Vva, Vwa, and is turned on for a predetermined period, and currents from the corresponding high potential side U-phase transistor 6UH, high potential side V phase transistor 6VH, and high potential side W phase transistor 6WH are supplied to the motor. After 10 is driven, it is turned off.
As a result of repeating these operations, the motor 10 is driven in the power running direction (traveling direction).

FIG. 10 is a voltage waveform during regeneration according to the embodiment.
When the vehicle accelerator is turned off, the motor 10 enters a free state and regenerative power is generated.
That is, when the induced voltage of the motor 10 becomes higher than the voltage obtained by adding the voltage of the battery E and the forward voltage of the free wheel diodes 7UH, 7UL, 7VH, 7VL, 7WH, and 7WL, The generated induced voltage is regenerated to the battery E via one of the corresponding freewheel diodes 7UH, 7UL, 7VH, 7VL, 7WH, 7WL.

  In this case, since the induced voltage decreases and the regenerative power decreases due to a decrease in the rotation speed of the motor 10, as shown in FIG. 10, the high potential side U-phase transistor 6UH, by the PWM drive signals Vua, Vva, Vwa, The high potential side V phase transistor 6VH and the high potential side W phase transistor 6WH are turned off, and the low potential side V phase transistor 6VL, the low potential side W phase transistor 6WL, and the low potential side W phase transistor 6WL are connected from the drive circuit 4 PWM drive is performed by the PWM drive signals Vua, Vva, and Vwa, the power is turned on / off, and the regenerative current of each phase is supplied to the battery E.

By the way, since the regenerative torque increases as the motor 10 approaches the stop, the voltage in the battery E and the drive circuit 4 increases due to the regenerative voltage.
Therefore, in this embodiment, when the regenerative voltage (inverter voltage) exceeds the voltage of the overvoltage determination threshold of the battery E, the reverse direction (reverse direction, reverse direction) with respect to the power running side of the motor 10. By generating a reverse torque by outputting a PWM drive signal for driving the motor 10, regenerative power is consumed by the motor 10, and voltage rise in the battery E and the drive circuit 4 is suppressed.

FIG. 11 is a voltage waveform at the time of overvoltage suppression (reverse rotation) of the embodiment.
Specifically, the high potential side U-phase transistor 6UH, the high potential side V phase transistor 6VH, and the high potential side W phase transistor 6WH are shifted in phase by 120 degrees by the PWM drive signals Vua, Vva, and Vwa to form a Hall IC. PWM drive is performed by PWM drive signals Vua, Vva, Vwa from the drive circuit 4 so that the ON period is located in the period in which the outputs of the fourth magnetic sensor 34d to the sixth magnetic sensor 34f are OFF. At the same time, the low-potential side V-phase transistor 6VL, the low-potential side W-phase transistor 6WL, and the low-potential side W-phase transistor 6WL are shifted in phase by 120 degrees, and are PWM driven by PWM drive signals Vua, Vva, Vwa from the drive circuit 4 Are turned on for a predetermined period, and the corresponding high potential side U-phase transistor 6UH, high potential side V-phase transistor By flowing a current from the motor 6VH and the high potential side W-phase transistor 6WH, after driving the motor 10, and turning off.
As a result of repeating these operations, the motor 10 is driven in the reverse direction (reverse direction).

FIG. 12 is a current waveform during overvoltage suppression (reverse rotation) of the embodiment.
As a result, the current waveform at the time of reverse rotation becomes as shown in FIG. 12, and the motor 10 shifts from the regenerative operation shown in FIG. 10 to the reverse operation mode so that the instructed reverse torque can be output. Corresponding current will flow.

FIG. 13 is an explanatory diagram of a change state of the battery current and the battery voltage.
As a result, as shown in the right side of the central part of FIG. 13A or an enlarged view of FIG. 13B, the electric power is consumed by the motor 10 when the motor 10 is rotated in reverse. BC decreases and the battery voltage BV is maintained at a substantially constant value, which shows that the overvoltage is suppressed.

FIG. 14 is a schematic explanatory diagram of the operation.
As shown in FIG. 14, the rotational speed RM of the motor 10 is constant until time t01 corresponding to power running. At this time, in order to drive the motor 10, the current IB of the battery E and the voltage VB of the battery E are also substantially constant (positive side: operating as a power source).
If the accelerator is turned off at time t01, the rotational speed RM of the motor gradually decreases. As a result, the motor 10 enters a regenerative operation, and the current IB of the battery E gradually increases as the regenerative current increases. (Negative side: charging operation).

By this charging operation, the voltage VB of the battery E gradually increases. When the voltage VB of the battery E reaches the overvoltage determination threshold value VREF of the battery E at time t02, the motor 10 performs the reverse operation. The mode IB is entered, and a current IB corresponding to a state where the instructed reverse torque can be output is passed. As a result, the rotation speed RM of the motor 10 further decreases and stops rotating at time t03.
As a result, the reverse rotation operation mode is terminated and a stop state is entered.

The above is the case where the motor 10 is stopped in the forward movement state, but it is also possible to similarly stop the motor 10 in the reverse movement state.
That is, when the accelerator is turned off in the reverse state, the operation mode is changed to the reverse operation mode, and the motor 10 is driven in the reverse direction (forward direction) to perform the same operation.

FIG. 15 is an explanatory diagram of an operation control map.
As shown in FIG. 15, since there is a region (shown as a reverse rotation region in FIG. 15) to shift to the reverse operation mode in both the forward direction and the reverse direction, the CPU 58 is based on the command speed ω _rm ^* and the torque. However, when control is performed in any one of the power running operation mode (power running region), the regenerative operation mode (regeneration region), or the reverse operation mode (reverse rotation region), the load that absorbs regenerative power is small. (For example, a state where the power consumption of a vehicle device such as a wiper or a headlight, an in-vehicle device such as an air conditioner or an audio device is low, or a state where the battery E is almost fully charged) does not return the regenerative power to the battery E. Therefore, it is possible to suppress the heat generation of the battery. Moreover, compared with control by interruption, the torque loss of the motor 10 does not occur, and there is a problem that the cost is increased by providing a breaker.
That is, according to the present embodiment, voltage information of the battery E can be suppressed without adding components, voltage information in the device such as the drive circuit 4 can be suppressed, and a highly reliable device is provided. It becomes possible to do.

Next, a modification of the embodiment will be described.
FIG. 16 is a block diagram showing a modified motor control system. In FIG. 16, the same parts as those in FIG. 8 are denoted by the same reference numerals.
The motor control system 100A of this modification example receives a command speed ω _rm ^* from a computer mounted on a vehicle and inputs the control speed to the control device 2 so as to drive the motor 10 at the command speed ω _rm ^* . That is, as shown in FIG. 10, the motor control system 100A roughly comprises a position / speed detection unit 82, a speed control unit 84, a drive signal generation unit 86, and an angle interpolation unit 88. This is realized by the CPU 58 provided in the drive circuit 4.
The position / speed detector 82 detects the position of the rotor 12 (that is, the magnetic pole position) θ _re and the rotational speed ω _rm of the rotor 12, outputs the rotational speed ω _rm to the speed controller 84, and also detects the magnetic pole position θ _re. Is output to the angle interpolation unit 88, and includes the rotor position detecting means 60 and the rotor speed detecting means 62 described above.

The speed control unit 84 calculates a voltage command value from the command speed ω _rm ^* input from a computer included in the vehicle and the rotational speed ω _rm detected by the position / speed detection unit 82, and outputs the voltage command value to the drive signal generation unit 86. To do. More specifically, the speed control unit 84 includes a speed controller 90 that calculates a torque command value from the command speed ω _rm ^* and the rotational speed ω _rm, and a duty that can be searched by the torque command value and the command speed ω _rm ^* . A (Duty) map 91 and an advance angle map 92 are provided.
The speed controller 90 includes a proportional (P) controller and an integral (I) controller, and compensates for the error by PI control based on the deviation between the command speed ω _rm ^* and the rotational speed ω _rm, and torque. Calculate the command value. The duty map 91 is a map that preliminarily defines the relationship between the command speed ω _rm ^* , the duty of a PWM drive signal described later, and torque. By searching the duty map 91 using the torque command value and the command speed ω _rm ^* , the duty at which the torque of the torque command value is obtained is determined. The advance angle map 92 is a map in which the relationship between the command speed ω _rm ^* , the advance angle, and the torque is defined in advance. That is, by searching the advance angle map 92 by the torque command value and the command speed omega _rm ^*, the optimum advance angle with respect to the torque command value and the command speed omega _rm ^* is obtained.
Then, a voltage command value including these lead angle and duty indication values is input to the drive signal generator 86.

The drive signal generation unit 86 includes a waveform generator 93 and a PWM drive signal generation unit 94. Waveform generator 93, U-phase based on the magnetic pole position theta _re of the rotor 12 from the angle interpolation unit 88 to be described later, together with the V-phase, and each phase of the sine wave signal sin [theta _re the W phase are inputted, the speed control unit 84 the voltage command value is input from the signal amplitude of each phase of the sine wave signal sin [theta _re adjusted by the voltage command value, a sine wave modulation signal, respectively ^{Vua *,} Vva *, the PWM drive signal generator 94 as Vwa ^* Output. The PWM drive signal generation unit 94 generates a PWM drive signal based on each sine wave modulation signal Vua ^* , Vva ^* , Vwa ^* . Specifically, the PWM drive signal generation unit 94 generates a PWM drive signal by a triangular wave comparison asynchronous method, and the voltage value of each sine wave modulation signal Vua ^* , Vva ^* , Vwa ^* and a triangular wave that is a carrier wave. Are generated, and a PWM drive signal is generated and output to the inverter circuit 6.

The angle interpolation unit 88 generates a sine wave signal sin θ _re based on the magnetic pole position θ _re of the rotor 12 output from the position / velocity detection unit 82, and outputs the sine wave signal sin θ _re to the drive signal generation unit 86. 97 and a trigonometric function calculator 98. The sine wave signal sin θ _re is a sine wave signal synchronized with the rotor position detection pulse signal Sa, as shown in FIG. In the present embodiment, since the pulse period of the rotor speed detection pulse signal Sb is 1/3 of the pulse period Ta of the rotor position detection pulse signal Sa, the rotor speed detection pulse signal Sb is output at every electrical angle of 60 degrees and the magnetic pole Input to the position interpolator 97. Each time the rotor speed detection pulse signal Sb is input, the magnetic pole position interpolator 97 outputs the magnetic pole position θ _re (= electric angle θ _re ) at that time to the trigonometric function calculator 98. The trigonometric function calculator 98 calculates the sine value (sin θ _re ) of the magnetic pole position θ _re every time the magnetic pole position θ _re (= electrical angle θ _re ) is input, and the waveform generator 93 as a sine wave signal sin θ _re. Output to.

Here, since the trigonometric function calculator 98 updates the value of the sine wave signal sin θ _re every time the magnetic pole position θ _re is input, the trigonometric function calculator 98 outputs a signal waveform whose value changes in a so-called step shape. Therefore, in the configuration in which the sine wave signal sin θ _re is output every 60 degrees of electrical angle, the sine wave signal sin θ _re becomes a rough signal Sj with a large deviation from the sine wave. In particular, when the rotational speed ω _rm of the motor 10 is slow, the output period Tc of the rotor speed detection pulse signal Sb becomes long. Therefore, the sine wave signal sin θ _re is actually a stepwise rough signal Sj on the time axis. The waveform is extended by, and the deviation from the sine wave becomes remarkable.

Therefore, in this modification, the magnetic pole position interpolator 97 interpolates the magnetic pole position θ _re at regular time intervals until the next rotor speed detection pulse signal Sb is input in addition to the input of the rotor speed detection pulse signal Sb. Is output to the trigonometric function calculator 98, thereby increasing the resolution of the sine wave signal sin _θre .
The resolution of the sine wave signal sin θ _re will be described in detail. If the basic period of the triangular wave used for the carrier wave for generating the PWM control signal is fc, and the command voltage frequency that is the frequency of the voltage command value input from the speed control unit 84 is fl. Since the waveform is broken if the motor 10 is driven by the triangular wave comparison asynchronous PWM control, and the sine wave modulation signals Vua ^* , Vva ^* , and Vwa ^* generated as PWM drive signals are not commanded at a sufficient speed, fc Waveform quality is maintained by setting / fl ≧ N (= 9) (where N = 9 is a value experiment or empirical value or the like as a value for obtaining a practical frequency in the basic period fc) It was requested from.)

Therefore, when the set maximum rotational speed of the motor 10 is X [rpm], the command voltage frequency fl = X / 60 × (number of poles / 2) [Hz] is obtained, so that the fundamental period of the carrier wave (carrier frequency) fc = Y [kHz] is set so as to satisfy the relationship of fc / fl ≧ N (= 9).
In this modified example, as shown in FIG. 16, when the set maximum rotational speed X is 3500 [rpm], the original angular resolution is 60, and the angular resolution is 512/360 [/ deg]. The wave signal sin θ _re is output.
Therefore, according to the present modification, in addition to the effects of the embodiment, the motor 10 can be driven more smoothly, smooth acceleration and deceleration can be performed, and the regenerative brake can be driven smoothly.

FIG. 17 is a block diagram showing a motor control system of another modification. Also in FIG. 17, the same parts as those in FIG. 8 are denoted by the same reference numerals, and the detailed description thereof is cited.
In the above-described embodiment, the motor control system 100 is exemplified as the motor control system 100 by the command speed ω _rm ^* , but the present invention is not limited to this. That is, as shown in FIG. 17, a motor control system 100B that drives the motor 10 based on the command torque T ^* may be used.

In FIG. 17, the command torque T ^* is determined according to a torque map that defines the relationship between the rotational speed ω _rm of the motor 10, the throttle opening, and the target torque command value. That is, the rotational speed ω _{rm of the} motor 10 is input from the position / speed detection unit 82 to the computer or the like included in the vehicle, and the throttle opening is input. Is input to the torque controller 190 of the motor drive system 100B as the command torque T ^* .
The torque controller 190 adjusts the output torque T so that the current output torque T becomes the command torque T ^* and outputs it to the duty map 91 and the advance angle map 92. The duty map 91 and the advance angle map 92 also _{receive the} rotational speed ω _rm , whereby the optimum duty and advance angle for the command torque T ^* and the rotational speed ω _rm are input to the drive signal generator 86. By outputting, drive control of the motor 10 based on the command torque T ^* is performed.

In the above description, control is performed by PI control. However, PID control (proportional / integral / derivative control) may be performed.
In the above description, an embodiment using an inverter has been described. However, a circuit in which a voltage conversion circuit such as a DC / DC converter circuit for stepping up or down the voltage of the battery E is incorporated between the battery E and the inverter circuit 6. It is also possible to apply to.

DESCRIPTION OF SYMBOLS 1 Motor drive system 2 Control apparatus 4 Drive circuit (overvoltage suppression apparatus)
4C Inverter voltage detection circuit (detector)
6 Inverter circuit 10 Motor 54 Magnetic pole position detection signal processing circuit 56 Pulse generation circuit 58 CPU (overvoltage suppression device)
82 Position / Speed Detection Unit 84 Speed Control Unit 86 Drive Signal Generation Unit 96 Voltage Type PWM Inverter 100, 100A, 100B Motor Control System E Battery Sa Rotor Position Detection Pulse Signal Sb Rotor Speed Detection Pulse Signal

Claims (4)

In an overvoltage suppression device that suppresses overvoltage in a motor drive device that regenerates power generated by a motor to a battery,
A detector for detecting the regenerative voltage;
The detected regenerative voltage is compared with the battery and a voltage threshold value of the battery, which is a voltage for starting an operation of suppressing an overvoltage by suppressing a voltage increase in the motor and the motor drive device ,
When the regenerative voltage exceeds the voltage threshold, the motor is moved in the power running direction so as to decrease the battery current increased with the increase of the regenerative current and keep the battery voltage at a constant value. A drive control circuit for driving in the opposite direction,
An overvoltage suppressing device comprising: The overvoltage suppressing device according to claim 1,
The motor and the battery are a power motor and a battery mounted on a vehicle,
An overvoltage suppressing device that functions as a power regenerative brake by regenerating power of the motor to the battery. The overvoltage suppressing device according to claim 1 or 2,
The battery voltage threshold is set as an overcharge prevention determination value for preventing overcharge of the battery,
An overvoltage suppressing device characterized by that. In a motor drive device that performs drive control of a motor,
A battery for supplying power to the motor;
A detector for detecting the regenerative voltage;
The detected regenerative voltage is compared with the battery and a voltage threshold value of the battery, which is a voltage for starting an operation of suppressing an overvoltage by suppressing a voltage increase in the motor and the motor drive device ,
When the regenerative voltage exceeds the voltage threshold, the motor is moved in the power running direction so as to decrease the battery current increased with the increase of the regenerative current and keep the battery voltage at a constant value. A drive control circuit for driving in the opposite direction,
A motor driving device comprising:

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