JP3667719B2 - Motor driving apparatus and motor driving method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to motor drive technology, and more particularly to PWM (pulse width modulation) motor drive technology.
[0002]
[Prior art]
  As PWM drive systems for brushless motors, a triangular wave slice system and a peak current detection system are known. The triangular wave slice method uses an error amplifier that passes a coil current through a detection resistor and outputs the difference between the voltage generated in the detection resistor and the torque command voltage as a slice level, slices a triangular wave with a certain period at this slice level, This is a method for determining the energization period of the coil. The peak current detection method is a method in which the current supply to the coil is stopped and the regenerative current mode is set when the voltage generated in the current detection resistor through which the coil current flows reaches the torque command voltage without using the error amplifier. .
[0003]
  FIG. 13 is a block diagram of a conventional peak current detection type motor driving apparatus. In FIG. 13, Hall elements 21A, 21B, and 21C detect the position of the rotor of the motor 10, and output Hall element outputs S11, S12, and S13 to the position detection circuit 22, respectively. The position detection circuit 22 obtains position signals S21, S22, and S23 based on the Hall element outputs S11, S12, and S13, and outputs them to the energized phase switching circuit 93. The position signals S21, S22 and S23 are signals obtained by shifting the phases of the hall element outputs S11, S12 and S13 by 30 °.
[0004]
  The energized phase switching circuit 93 determines the energized phase according to the position signals S21, S22, and S23. At this time, the energized phase switching circuit 93 does not flow the phase current of one of the three phases in order to facilitate measurement of the phase current. The logic control circuit 95 is set when the reference pulse PI is input, and controls the supply of current to the motor 10 by changing the level of the signal output to the energized phase switching circuit 93. The reference pulse PI is a periodic pulse.
[0005]
  FIG. 14 is a graph showing changes of each phase current of the motor driven by the motor driving device of FIG. 13 with respect to time. FIG. 14 shows the phase currents I1, I2, and I3 of the U-phase, V-phase, and W-phase, and the current flowing from the drive transistors 1 to 6 toward the motor 10 is positive. As shown in FIG. 14, since the phase current of one phase is always zero, one of the phase currents changes abruptly at every electrical angle of 60 °.
[0006]
  Now, it is assumed that the logic control circuit 95 is set by the reference pulse PI. The energization phase switching circuit 93 conducts only the W-phase upper arm side drive transistor 5 and the U-phase lower arm side drive transistor 2, for example. At this time, since a current flows through the current detection resistor 7 via the W-phase coil 13 and the U-phase coil 11, the magnitude of this current can be detected as a voltage generated in the current detection resistor 7. Since this current flows through the inductive coil, it gradually increases after the drive transistors 2 and 5 are turned on.
[0007]
  When the current increases and the voltage generated in the current detection resistor 7 reaches the torque command voltage TI, the output level of the comparator 96 changes and the logic control circuit 95 is reset. The logic control circuit 95 inverts the level of the signal output to the energized phase switching circuit 93, and the energized phase switching circuit 93 makes the drive transistor 2 non-conductive.
[0008]
  Thus, the period from when the logic control circuit 95 is set to when it is reset becomes the on-duty period of the switching operation. After the logic control circuit 95 is reset, the current flowing through the coils 11 and 13 tends to continue flowing, so that the regenerative current flows through the diode 1D existing between the source and drain of the driving transistor 1. Since the regenerative current does not pass through the current detection resistor 7, the voltage generated in the current detection resistor 7 becomes zero during regeneration.
[0009]
  Although the regenerative current gradually decreases, when the reference pulse PI is input again, the logic control circuit 95 is set and the energized phase switching circuit 93 makes the drive transistor 2 conductive. Such an operation is repeated until the energized phase switching circuit 93 switches the energized phase. As described above, the drive current that flows when the logic control circuit 95 is set and the regenerative current that flows when the logic control circuit 95 is reset flow alternately. Can do.
[0010]
  FIG. 15 is a graph showing the current detection resistance voltage (motor current detection signal) MC, V-phase and W-phase phase currents I2 and I3 in the vicinity of time t = tz in FIG. In FIG. 15, a period T91 is a period in which drive currents of U-phase and V-phase currents flow, and this current flows through the current detection resistor 7. The period T92 is a period in which the U-phase and V-phase currents flow as the regenerative current. The period T93 is a period in which drive currents of U-phase and W-phase currents flow, and this current flows through the current detection resistor 7. The period T94 is a period in which the U-phase and W-phase currents flow as the regenerative current.
[0011]
[Problems to be solved by the invention]
  However, the conventional motor driving apparatus as shown in FIG. 13 has a problem that the phase current changes abruptly as shown in FIG. 14, so that the motor vibrates or generates electromagnetic noise when the phase current is switched. It was.
[0012]
  In order to prevent such a problem from occurring, each phase current may be controlled so as not to change suddenly. However, in order to detect and control a plurality of phase currents, the number of phases equal to the number of phases may be controlled. A current sensing resistor was required. Since it is difficult to incorporate a current detection resistor into an integrated circuit, there is a problem that if the number of current detection resistors is large, the scale of the device increases and costs increase.
[0013]
  Further, since resistance characteristics generally vary, there is a problem in that current detection characteristics differ from phase to phase when current detection resistors corresponding to each phase are used. For example, even if the magnitudes of the two phase currents are actually the same, the magnitudes of the detected currents may be different.
[0014]
  SUMMARY OF THE INVENTION The present invention solves the above problems, and aims to reduce motor vibration and electromagnetic noise by using a single current detection resistor and controlling a plurality of phase currents so as not to change suddenly. And
[0015]
[Means for Solving the Problems]
  In order to solve the above-mentioned problem, the means of the invention of claim 1 includes a plurality of output circuits each having an upper arm side switching element and a lower arm side switching element connected in series, and the upper circuit in each of the output circuits. A motor driving device that supplies current to a motor from a connection point between an arm side switching element and a lower arm side switching element, and is connected in series and in common to the plurality of output circuits, and is connected to the plurality of output circuits. A current detection resistor for detecting a supplied current; a position detection unit that outputs a position signal corresponding to the position of the rotor of the motor; and one switching element in any one of the plurality of output circuits Is selected according to the position signal, and is turned on during a period corresponding to a predetermined electrical angle, and the switching element to be turned on is When the switching element is a lower arm side switching element, the lower arm side switching element in any one of the remaining plurality of output circuits is switched to conduct when the switching element is a lower arm side switching element. And a switching element that performs the switching operation in each of a plurality of periods in which a period corresponding to the predetermined electrical angle is divided A first period in which a plurality of switching elements are conducted, and a second period in which any one of the plurality of switching elements conducted in the first period is continuously conducted. According to the input torque command signal and the voltage generated in the current detection resistor. Te, wherein due to energization phase switching circuit generates a switching operation control signal for controlling the switching operation, and a conduction period control unit to outputThe energization period control unit includes a first target signal corresponding to a target value of a current to be passed through the current detection resistor in the first period, the torque command signal, and the position according to the torque command signal. A phase-specific torque signal generation circuit that alternately outputs a second target signal corresponding to a target value of a current to be passed through the current detection resistor in the second period, which is obtained according to a signal; and the current detection resistor It is determined whether or not the voltage generated in the circuit exceeds the output of the phase-specific torque signal generation circuit, and a comparator that outputs the result, a reference pulse that defines the cycle of the switching operation, and the output of the comparator And a logic control circuit that generates and outputs the switching operation control signal.
[0016]
  According to the first aspect of the present invention, the first period during which the plurality of switching elements are conducted, and the second period during which one switching element among the plurality of switching elements conducted during the first period is continuously conducted; Therefore, it is possible to control a plurality of phase currents using a single current detection resistor. For this reason, PWM control in which the magnitudes of the phase currents do not vary is enabled, a sudden change in the phase current can be avoided, and motor vibration and electromagnetic noise during phase switching can be reduced.
[0017]
  According to a second aspect of the present invention, in the motor drive device according to the first aspect,,PreviousWhen the comparator determines that the voltage generated in the current detection resistor exceeds the output of the phase-specific torque signal generation circuit for the first period, the logic control circuit ends the first period. When the voltage generated in the current detection resistor is determined to exceed the output of the phase-specific torque signal generation circuit for the second period, the switching operation control signal is generated so as to end the second period. Output.
[0018]
  According to the invention of claim 2, an appropriate switching operation control signal can be generated.
[0019]
  According to a third aspect of the present invention, in the motor driving device according to the second aspect, the logic control circuit is set by the reference pulse, and the first latch that uses the output of the comparator as a reset input; A second latch that is set by a reference pulse; a logic circuit that receives the output of the first latch and the output of the comparator as inputs and provides the obtained output as a reset input to the second latch; And the output of the first and second latches is output as the switching operation control signal, and the first latch outputs the voltage generated in the current detection resistor as the output of the comparator. The logic circuit is reset when the signal indicates that the target signal exceeds the target signal, and the output of the first latch is reset when the first latch is reset. The output of the comparator is output when it indicates that the first latch is not output, and the output of the comparator is not output when the first latch is not reset. The latch of 2 indicates that the logic circuit outputs the output of the comparator, and the output of the comparator indicates that the voltage generated in the current detection resistor exceeds the second target signal. When it is reset.
[0020]
  According to the invention of claim 3, since the logic circuit is provided, the operation of the second latch can be ensured, and the malfunction of the motor driving device can be reduced.
[0021]
  According to a fourth aspect of the present invention, in the motor drive device according to the third aspect, the logic control circuit further includes a delay circuit that delays and outputs the output of the first latch for a predetermined time. The first latch provides its output to the logic circuit via the delay circuit.
[0022]
  According to the invention of claim 4, malfunctions due to noise of the second latch can be reduced.
[0023]
  The invention of claim 5Includes a plurality of output circuits each having an upper arm side switching element and a lower arm side switching element connected in series, and the motor is connected to the upper arm side switching element and the lower arm side switching element in each of the output circuits. A motor driving device for supplying a current to the plurality of output circuits in series and in common, and a current detection resistor for detecting the current supplied to the plurality of output circuits; and the motor A position detection unit that outputs a position signal corresponding to the position of the rotor and one switching element in any one of the plurality of output circuits is selected according to the position signal and corresponds to a predetermined electrical angle The switching element that conducts during the period to be When the switching element is a lower arm side switching element, the lower arm side switching element in any one of the remaining plurality of output circuits is switched to conduct when the switching element is a lower arm side switching element. And a switching element that performs the switching operation in each of a plurality of periods in which a period corresponding to the predetermined electrical angle is divided A first period in which a plurality of switching elements are conducted, and a second period in which any one of the plurality of switching elements conducted in the first period is continuously conducted. According to the input torque command signal and the voltage generated in the current detection resistor The generates switching operation control signal for controlling the switching operation of the conduction phase switch circuit, a conduction period control unit for outputting,The energization period control unit includes a first target signal corresponding to a target value of a current to be passed through the current detection resistor in the first period, the torque command signal, and the position signal according to the torque command signal. A phase-specific torque signal generating circuit that outputs a second target signal corresponding to a target value of the current to be passed through the current detection resistor in the second period, and a voltage generated in the current detection resistor Determines whether or not the first target signal exceeds the first target signal, and outputs a result of the first comparator and whether or not the voltage generated in the current detection resistor exceeds the second target signal. The switching operation control signal is generated according to a second comparator that determines and outputs the result, a reference pulse that defines a cycle of the switching operation, and outputs of the first and second comparators. Output Bei and that logic control circuitGetIs.
[0024]
  According to the fifth aspect of the present invention, the first and second comparators are unlikely to malfunction, so that stable operation can be performed.
[0025]
  According to a sixth aspect of the present invention, in the motor drive device according to the fifth aspect, the logic control circuit is configured so that the voltage generated in the current detection resistor exceeds the first target signal. If the second comparator determines that the voltage generated in the current detection resistor exceeds the second target signal, the second period is terminated. The switching operation control signal is generated and output so as to terminate the process.
[0026]
  Claims7In the invention of claim6In the motor drive device according to claim 1, the logic control circuit is set by the reference pulse, a first latch having an output of the first comparator as a reset input, and a second latch set by the reference pulse. A latch, and a logic circuit that receives the output of the first latch and the output of the second comparator as inputs and provides the obtained output as a reset input to the second latch, An output of a second latch is output as the switching operation control signal, and the first latch outputs an output of the first comparator, and a voltage generated in the current detection resistor is the first target signal. The logic circuit indicates that the output of the first latch indicates that the first latch is reset. The output of the second comparator is output when it is, and the output of the second comparator is not output when it indicates that the first latch is not reset, In the second latch, the logic circuit outputs the output of the second comparator, and the output of the second comparator indicates that the voltage generated in the current detection resistor exceeds the second target signal. Indicates that it is reset.
[0027]
  Claim7According to the invention, since the logic circuit is provided, the operation of the second latch can be ensured, and the malfunction of the motor driving device can be reduced.
[0028]
  Claims8In the invention of claim1Alternatively, in the motor drive device described in 5, the period of the reference pulse is substantially constant.
[0029]
  Claim8According to this invention, since the cycle of the timing for turning on the driving transistor is constant, it is easy to take measures to make it less susceptible to noise caused by switching.
[0030]
  Claims9In the invention of claim1Alternatively, the phase-specific torque signal generation circuit uses a voltage corresponding to the torque command signal as the first target signal, and based on the position signal and the first target signal. A sawtooth wave having a period corresponding to the predetermined electrical angle and a peak value substantially equal to the first target signal is generated and used as the second target signal.
[0031]
  Claim9According to this invention, the waveform of the phase current can be formed into a substantially trapezoidal shape, and a sudden change in the phase current can be avoided.
[0032]
  The invention of claim 10 includes a plurality of output circuits having an upper arm side switching element and a lower arm side switching element connected in series as a motor driving method, in series with the plurality of output circuits, and A current detection resistor for detecting current supplied to the plurality of output circuits in common, and a motor from a connection point between the upper arm side switching element and the lower arm side switching element in each of the output circuits A step of obtaining a position signal corresponding to the position of the rotor of the motor, and one switching element in any one of the plurality of output circuits according to the position signal. Selecting and conducting in a period corresponding to a predetermined electrical angle, and the switching element to be conducted When the switching element is an arm-side switching element, the lower arm-side switching element in any one of the remaining plurality of the output circuits performs a switching operation, and when the switching element to be conducted is the lower arm-side switching element, the plurality of outputs And a step of causing the upper arm side switching elements in any one of the remaining plurality of circuits to perform a switching operation.IsIn each of a plurality of periods divided by a period corresponding to the predetermined electrical angle, among the switching elements that perform the switching operation, a first period in which a plurality of switching elements are conducted, and a first period The torque command signal input so that there is a second period in which any one of the plurality of conducting switching elements is continuously conducted.And the second period determined according to the first target signal corresponding to the target value of the current to be passed through the current detection resistor in the first period, and the torque command signal and the position signal. And a second target signal corresponding to a target value of the current to be passed through the current detection resistor, and alternately compared with a voltage generated in the current detection resistor, and a reference pulse defining the result and the cycle of the switching operation Depending onThe switching operation is controlled.
[0033]
  The invention of claim 11 is a motor driving method.A plurality of output circuits each having an upper arm side switching element and a lower arm side switching element connected in series are provided, and are connected in series and in common to the plurality of output circuits, and are supplied to the plurality of output circuits. A motor driving device for supplying a current to a motor from a connection point between the upper arm side switching element and the lower arm side switching element in each of the output circuits. A step of obtaining a position signal according to the position of one of the plurality of output circuits, and selecting one switching element in any one of the plurality of output circuits according to the position signal, and conducting in a period corresponding to a predetermined electrical angle. Steps,
  When the switching element to be conducted is an upper arm side switching element, the lower arm side switching element in any of the remaining plurality of the plurality of output circuits is caused to perform a switching operation, and the switching element to be conducted is a lower arm side switching element. In some cases, a step of switching the upper arm side switching element in any one of the remaining plurality of the plurality of output circuits is performed, and the step of performing the switching operation is divided by a period corresponding to the predetermined electrical angle. In each of a plurality of periods, the switch Among the switching elements that perform the switching operation, a first period in which the plurality of switching elements are conducted, and a second period in which any one of the plurality of switching elements that are conducted in the first period is continuously conducted A first target signal corresponding to a target value of a current to be passed through the current detection resistor in the first period, the torque command signal, and the torque command signal according to the input torque command signal The second target signal corresponding to the target value of the current to be passed through the current detection resistor in the second period, which is obtained according to the position signal, is compared with the voltage generated in the current detection resistor, The switching operation is controlled in accordance with a reference pulse that defines a cycle of the switching operation.
[0034]
DETAILED DESCRIPTION OF THE INVENTION
  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, as an example, a case where a motor driving device drives a three-phase brushless motor will be described.
[0035]
  (First embodiment)
  FIG. 1 is a block diagram of a motor drive device according to a first embodiment of the present invention. 1 includes U-phase, V-phase, and W-phase upper arm side drive transistors 1, 3, and 5, U-phase, V-phase, and W-phase lower arm-side drive transistors 2, 4, and 6, and a diode 1D. , 2D, 3D, 4D, 5D, 6D, current detection resistor 7, Hall element circuit 21, position detection circuit 22, energized phase switching circuit 23, predrive circuit 24, and phase-specific torque signal generation circuit 30 And a logic control circuit 40 and a comparator 51. On the other hand, the motor 10 includes a U-phase coil 11, a V-phase coil 12, and a W-phase coil 13. The phase-specific torque signal generation circuit 30, the logic control circuit 40, and the comparator 51 constitute an energization period control unit 100. The Hall element circuit 21 and the position detection circuit 22 constitute a position detection unit.
[0036]
  The driving transistors 1 to 6 are n-type MOS (metal oxide semiconductor) transistors. The anode and cathode of the diode 1D are connected to the source and drain of the driving transistor 1, respectively. Similarly, diodes 2D to 6D are connected to the drive transistors 2 to 6, respectively. The drains of the drive transistors 1, 3, 5 are connected to the power supply VCC, and the sources of the drive transistors 2, 4, 6 are connected to one end of the current detection resistor 7. The other end of the current detection resistor 7 is grounded. The drive transistors 1 to 6 operate as switching elements.
[0037]
  The drive transistors 1 and 2 and the diodes 1D and 2D operate as a U-phase output circuit. The drive transistors 3 and 4 and the diodes 3D and 4D operate as a V-phase output circuit. The drive transistors 5 and 6 and the diodes 5D and 6D operate as a W-phase output circuit.
[0038]
  The source of the driving transistor 1 is connected to the drain of the driving transistor 2 and further connected to one end of the U-phase coil 11 of the motor 10. The source of the drive transistor 3 is connected to the drain of the drive transistor 4 and further connected to one end of the V-phase coil 12 of the motor 10. The source of the drive transistor 5 is connected to the drain of the drive transistor 6 and further connected to one end of the W-phase coil 13 of the motor 10. The other end of the U-phase coil 11 is connected to the other ends of the V-phase coil 12 and the W-phase coil 13.
[0039]
  Here, the current flowing from the drive transistors 1 and 2 toward the U-phase coil 11 is referred to as a U-phase current I1. Similarly, the current flowing from drive transistors 3 and 4 toward V-phase coil 12 is referred to as V-phase current I2, and the current flowing from drive transistors 5 and 6 toward W-phase coil 13 is referred to as W-phase current I3. The current flowing from the driving transistors 1 to 6 toward the coils 11 to 13 is referred to as a discharge current, and the current in the opposite direction is referred to as a sink current. The direction of the discharge current is the positive direction of each phase current. Since the coils 11 to 13 of the motor 10 are Y-connected, each phase current is equal to the current flowing through the corresponding coil.
[0040]
  The Hall element circuit 21 includes Hall elements 21A, 21B, and 21C. Each of the hall elements 21A, 21B, and 21C detects the position of the rotor of the motor 10, and outputs hall element outputs S11, S12, and S13 to the position detection circuit 22. The position detection circuit 22 obtains position signals S21, S22, S23 and PS based on the Hall element outputs S11, S12 and S13, and separates the position signals S21, S22 and S23 into the energized phase switching circuit 23 and the position signal PS. Output to the torque signal generation circuit 30.
[0041]
  The phase-specific torque signal generation circuit 30 corresponds to the target value of the current flowing through the current detection resistor 7 based on the position signal PS, the torque command voltage (torque command signal) TI, the reference pulse PI, and the output CP of the comparator 51. A voltage signal TP to be generated is generated and output to the positive input terminal of the comparator 51. The voltage generated in the current detection resistor 7 (source potential of the drive transistors 2, 4, 6) is input to the negative input terminal of the comparator 51 as the motor current detection signal MC. The comparator 51 outputs the output CP to the phase-specific torque signal generation circuit 30 and the logic control circuit 40. Further, a reference pulse PI is input to the logic control circuit 40. The logic control circuit 40 generates switching operation control signals F1 and F2 that define a period during which the drive transistors 1 to 6 are turned on and outputs the switching operation control signals F1 and F2 to the energized phase switching circuit 23.
[0042]
  Based on the position signals S21, S22, S23 and the control signals F1, F2, the energized phase switching circuit 23 selects one to be conducted among the drive transistors 1 to 6 and instructs the predrive circuit 24. The predrive circuit 24 outputs a signal to the gates of the drive transistors 1 to 6 according to the output of the energized phase switching circuit 23 to control conduction / non-conduction of the drive transistors 1 to 6.
[0043]
  FIG. 2 is a graph showing target waveforms of the phase currents I1 to I3 of the motor 10. The motor drive device of FIG. 1 controls the supply of current to the motor 10 as shown in FIG. 2 so that the phase currents I1 to I3 of the motor 10 do not change suddenly. The motor drive device of FIG. 1 divides the electrical angle 360 ° of the motor 10 into, for example, six parts, and every angle corresponding to the divided electrical angle, that is, the angle corresponding to the divided electrical angle of the rotor of the motor 10. Each time the motor 10 rotates, the current of the motor 10 is controlled while switching the energized phase.
[0044]
  For example, the period TU1 in FIG. 2 is a period corresponding to an electrical angle of 60 °. In the period TU1, the U-phase current I1 is a discharge current, and its magnitude is substantially constant. The V-phase current I2 is a sink current, and its magnitude gradually decreases with time t. The W-phase current I3 is a sink current, and its magnitude gradually increases from 0 with time t. Therefore, in the period TU1, the U-phase upper arm side drive transistor 1 is continuously conducted. Further, the V-phase and W-phase lower arm side drive transistors 4 and 6 are switched so that the V-phase current I2 and the W-phase current I3 are as shown in FIG. And the non-conduction period.
[0045]
  FIG. 3 is a block diagram illustrating an example of the configuration of the energization period control unit 100 of FIG. The energization period control unit 100 includes a phase-specific torque signal generation circuit 30, a logic control circuit 40, and a comparator 51. The phase-specific torque signal generation circuit 30 of FIG. 3 includes a both-edge differentiation circuit 31, a constant current source 32, switches 33 and 36, a capacitor 34, a level control circuit 35, and an RS flip-flop 37. . The logic control circuit 40 of FIG. 3 includes an RS flip-flop 41 as a first latch, an RS flip-flop 42 as a second latch, a delay circuit 43, inverters 44 and 45, and a NAND gate 46. ing. Inverters 44 and 45 and NAND gate 46 operate as logic circuit 49.
[0046]
  FIG. 4 is a graph showing signals relating to the position detection circuit 22 and the phase-specific torque signal generation circuit 30. The position detection circuit 22 obtains a position detection signal S21 indicating the rotor position of the motor 10 based on the Hall element outputs S11 and S12. Here, as an example, the difference between the Hall element outputs S11 and S12 is defined as a position detection signal S21 (S21 = S11−S12). The Hall element outputs S11 and S12 are approximate sine waves. When the phase of the Hall element output S11 is 120 ° ahead of S12, the phase of the position detection signal S21 is 30 ° ahead of the Hall element output S11. . Similarly, the position detection circuit 22 obtains the position detection signals S22 and S23 by, for example, S22 = S12−S13 and S23 = S13−S11.
[0047]
  The position detection circuit 22 obtains a position detection signal PS based on the obtained position detection signals S21, S22, S23. The position detection signal PS rises when the position detection signal S21 changes from negative to positive, and falls when the position detection signal S23 changes from positive to negative. When the position detection signal S22 changes from negative to positive Rises when the position detection signal S21 changes from positive to negative, rises when the position detection signal S23 changes from negative to positive, and rises when the position detection signal S22 changes from positive to negative. This signal repeats the falling pulse. As shown in FIG. 4, the edge timing of the position detection signal PS is the timing at which the waveforms of the Hall element outputs S11, S12, and S13 cross.
[0048]
  The operation of the phase-specific torque signal generation circuit 30 will be described with reference to FIGS. A position signal PS output from the position detection circuit 22 is input to the both edge differentiation circuit 31. The both edge differentiating circuit 31 outputs a reset pulse signal S31 which is “L” for a certain period when the edge of the position signal PS is detected and becomes “H” for other periods as a control signal to the switch 33 (“H”, “H”). L ″ represents a logical high potential and a low potential, respectively).
[0049]
  One end of the capacitor 34 is connected to the output of the constant current source 32 and is grounded via the switch 33. The other end of the capacitor 34 is grounded. The capacitor 34 is charged by the current output from the constant current source 32, and the switch 33 is turned on only when the reset pulse signal S31 is “L” to discharge the capacitor 34. Therefore, the voltage S32 of the capacitor 34 becomes a sawtooth wave as shown in FIG.
[0050]
  The level control circuit 35 receives the torque command voltage TI and the voltage S32 as inputs, and outputs a signal TS obtained by multiplying the voltage S32 by a gain so that the peak of the voltage S32 becomes equal to the torque command voltage TI to the switch 36. . The switch 36 selects either the torque command voltage TI as the first target signal or the signal TS as the second target signal according to the output of the RS flip-flop 37, and the comparator 51 as the signal TP. Output to. The RS flip-flop 37 is set by the reference pulse PI and reset by the output of the comparator 51. Therefore, the switch 36 alternately outputs the signal TI and the signal TS as the signal TP (see FIGS. 3 and 5).
[0051]
  FIG. 5 is a graph showing input / output signals of the logic control circuit 40 and the comparator 51 of FIG. FIG. 6 is a graph showing phase currents in the motor drive device of FIG. 5 and 6 show an enlarged view around t = t1 in FIGS.
[0052]
  The operation of the logic control circuit 40 and the current flowing through the motor 10 will be described with reference to FIGS. 3, 5, and 6. As shown in FIG. 5, the reference pulse PI is a pulse signal having a substantially constant period, and this period is a reference for the period of the PWM control.
[0053]
  The reference pulse PI is input to the set terminals of the RS flip-flop 37 and the RS flip-flops 41 and 42 in FIG. When the reference pulse PI falls, the RS flip-flop 37 is set and the output is set to “H”. At this time, the switch 36 selects the torque command voltage TI and outputs it to the comparator 51 as a signal TP. Since the RS flip-flops 41 and 42 are also set, the control signals F1 and F2 are both “H”.
[0054]
  It is assumed that the energized phase switching circuit 23 determines that it is currently within the period TU1 of FIG. 2 based on the position signals S21, S22, and S23. As shown in FIG. 2, this period TU1 is a period in which the U-phase current I1 is a discharge current having a substantially constant magnitude. In the period TU1, since the U-phase current I1 is the only discharge current, the energized phase switching circuit 23 keeps the drive transistor 1 conductive. Since the V-phase current I2 and the W-phase current I3 are sink currents and need to be changed in magnitude, the energized phase switching circuit 23 performs a switching operation on the drive transistors 4 and 6 according to the control signals F1 and F2. Make it. In the period TU1, the energized phase switching circuit 23 turns on the drive transistor 4 when the control signal F1 is “H”, and turns on the drive transistor 6 when the control signal F2 is “H”. The drive transistors 2, 3, and 5 are turned off.
[0055]
  When the control signals F1 and F2 both become “H”, the energized phase switching circuit 23 makes the drive transistors 4 and 6 conductive (first period T1). At this time, current flows from the drive transistor 1 toward the U-phase coil 11 and flows as current. The current flowing through the U-phase coil 11 is divided into the V-phase coil 12 and the W-phase coil 13, and flows as a sink current toward the drive transistors 4 and 6, respectively.
[0056]
  In the state where the drive transistors 4 and 6 are conducting at the same time, both the V-phase current I2 and the W-phase current I3 flowing through the V-phase coil 12 and the W-phase coil 13 flow through the current detection resistor 7, respectively. The magnitude of the current flowing through the current detection resistor 7 is equal to the U-phase current I1 flowing through the U-phase coil 11. A voltage proportional to the magnitude of the current flowing through the current detection resistor 7 is generated, and this voltage is input to the negative input terminal of the comparator 51 as the motor current detection signal MC.
[0057]
  Since the U-phase coil 11, the V-phase coil 12, and the W-phase coil 13 are inductive loads, the V-phase current I2 and the W-phase current I3 gradually increase in the period T1 after the drive transistors 4 and 6 are turned on. (See FIG. 6). Therefore, the motor current detection signal MC also gradually increases. When the voltage of the motor current detection signal MC reaches the voltage of the signal TP (see FIG. 5), the comparator 51 changes the output CP to “L”. Then, the RS flip-flop 41 is reset and the output is inverted to “L”, so that the control signal F1 becomes “L”, and the process proceeds to the second period T2.
[0058]
  During the period T2, since the control signals F1 and F2 are “L” and “H”, respectively, the energized phase switching circuit 23 makes the drive transistor 4 non-conductive. The driving transistor 6 remains conductive. When the drive transistor 4 becomes non-conductive, the regenerative current of the V-phase coil 12 flows through the diode 3D between the source and drain of the drive transistor 3 and the drive transistor 1. The V-phase current I2 flowing as the regenerative current gradually decreases (see FIG. 6). At this time, since only the current flowing in the W-phase coil 13 flows in the current detection resistor 7, the current in the W-phase coil 13 can be detected without being affected by the current in the V-phase coil 12.
[0059]
  After shifting to the period T2, the level of the signal TP input to the positive input terminal of the comparator 51 falls to the potential (bottom level) of the signal TS, but when the current of the V-phase coil 12 does not flow through the current detection resistor 7. Since the level of the motor current detection signal MC becomes lower and lower than the bottom level of the signal TP, the output CP of the comparator 51 returns to “H” again (see FIG. 5).
[0060]
  In addition, when the period shifts to the period T2, the output of the delay circuit 43 becomes “L” following the control signal F1 when a preset predetermined time elapses, and the output of the inverter 44 shifts to “H”. . While the output of the inverter 44 is “L”, the output of the NAND gate 46 is “H”, and the RS flip-flop 42 is not reset regardless of the change of the output CP of the comparator 51. Then, after the output of the delay circuit 43 shifts to “L”, the RS flip-flop 42 is reset only when the output of the comparator 51 becomes “L” and the output of the inverter 45 becomes “H”.
[0061]
  During the period T2, since the drive transistors 1 and 6 are still conducting, the current of the W-phase coil 13 continues to increase (see FIG. 6), and the current flowing through the current detection resistor 7 continues to increase. When the voltage of the motor current detection signal MC increases and reaches the voltage of the signal TP output from the phase-specific torque signal generator 30, the comparator 51 sets the output CP to “L”. Then, the RS flip-flop 42 is reset, the control signal F2 becomes “L”, and the operation proceeds to the period T3.
[0062]
  During the period T3, the control signals F1 and F2 are both “L”, so that the energized phase switching circuit 23 makes the drive transistors 4 and 6 non-conductive.
[0063]
  Thus, the drive transistor 4 is turned on during the period when the control signal F1 is “H”, and the drive transistor 6 is turned on during the period when the control signal F2 is “H”. In a period T1 in which both of the control signals F1 and F2 are “H”, control is performed so that the sum of the currents flowing through the V-phase coil 12 and the W-phase coil 13 becomes a value corresponding to the signal TP. Are controlled so that the current flowing through the W-phase coil 13 becomes a value corresponding to the signal TP during the period T2 when “L” and “H” are respectively. That is, among the two-phase (V-phase and W-phase) drive transistors 4 and 6 that perform the switching operation in the period TU1, the drive transistor 4 in the phase (V-phase) whose current is to be reduced in the period TU1 is first displayed. (See FIG. 2).
[0064]
  In the period T3 in which the control signals F1 and F2 are both “L”, only the regenerative current flows through the coils 11-13. The V-phase current I2 and the W-phase current I3 that flow as regenerative current gradually decrease (see FIG. 6). When the reference pulse PI is input to the phase-specific torque signal generation circuit 30 and the logic control circuit 40, the control signals F1 and F2 both become “H” again, and the same process is repeated thereafter.
[0065]
  The logic control circuit 40 of FIG. 3 may not include the delay circuit 43 when malfunction does not occur due to switching noise of the drive transistors 1 to 6.
[0066]
  FIG. 7 is an explanatory diagram showing a path of a current flowing through the motor 10 in the period T1. As shown in FIG. 7, in the period T1, the V-phase current I2 flowing through the V-phase coil 12 is in the order from the power source to the drive transistor 1, the U-phase coil 11, the V-phase coil 12, the drive transistor 4, and the current detection resistor 7. Flowing. On the other hand, the W-phase current I3 flowing through the W-phase coil 13 flows from the power source in the order of the drive transistor 1, the U-phase coil 11, the W-phase coil 13, the drive transistor 6, and the current detection resistor 7. Therefore, the sum of the V-phase current I2 and the W-phase current I3 can be detected from the voltage generated in the current detection resistor 7.
[0067]
  FIG. 8 is an explanatory diagram showing a path of a current flowing through the motor 10 in the period T2. As shown in FIG. 8, in the period T2, the V-phase current I2 flowing through the V-phase coil 12 is a regenerative current, and is a loop in the order of the drive transistor 1, the U-phase coil 11, the V-phase coil 12, and the diode 3D. Flowing. On the other hand, the W-phase current I3 flowing through the W-phase coil 13 flows from the power source in the order of the driving transistor 1, the U-phase coil 11, the W-phase coil 13, the driving transistor 6, and the current detection resistor 7, as in FIG. Therefore, only the W-phase current I3 can be detected from the voltage generated in the current detection resistor 7.
[0068]
  FIG. 9 is an explanatory diagram illustrating a path of a current flowing through the motor 10 in the period T3. As shown in FIG. 9, in the period T3, the V-phase current I2 flowing through the V-phase coil 12 is a regenerative current and flows in a loop shape as in FIG. On the other hand, the W-phase current I3 flowing through the W-phase coil 13 is also a regenerative current and flows in a loop in the order of the drive transistor 1, the U-phase coil 11, the W-phase coil 13, and the diode 5D. Therefore, no current flows through the current detection resistor 7. As described above, the drive current that flows through the drive transistors of the output circuits of the respective phases and the regenerative current that flows through the diodes of the output circuits of the respective phases alternately flow through the coils 11 to 13.
[0069]
  Next, the operation of the motor drive device of FIG. 1 during the period TU2 of FIG. 2 will be described. As shown in FIG. 2, this period TU2 is a period in which the U-phase current I1 is a suction current having a substantially constant magnitude. In the period TU2, since the U-phase current I1 is the only sink current, the energized phase switching circuit 23 keeps the drive transistor 2 conductive. Since the V-phase current I2 and the W-phase current I3 are discharge currents and need to be changed in magnitude, the energized phase switching circuit 23 causes the drive transistors 3 and 5 to perform a switching operation. In the period TU2, the energized phase switching circuit 23 turns on the drive transistor 3 when the control signal F1 is “H”, and turns on the drive transistor 5 when the control signal F2 is “H”. The drive transistors 1, 4 and 6 are turned off.
[0070]
  The energized phase switching circuit 23 makes the drive transistors 3 and 5 conductive when the control signals F1 and F2 both become “H”. When the control signals F1 and F2 are “L” and “H”, respectively, the driving transistor 3 is turned off. When the control signals F1 and F2 are both “L”, the drive transistor 5 is also turned off.
[0071]
  As a result, in the period TU2, the flow directions of the U-phase current I1, the V-phase current I2, and the W-phase current I3 are opposite to those in the period TU1. Since other points are the same as those in the period TU1, detailed description thereof is omitted.
[0072]
  The operation of the motor driving device in FIG. 1 in the periods TV1 and TW1 is the same as that in the period TU1 except for the following points. In other words, during the period TV1 in which the V-phase current I2 is a discharge current having a substantially constant magnitude, the energized phase switching circuit 23 keeps the driving transistor 3 continuously in place of the driving transistor 1. In addition, the energized phase switching circuit 23 causes the drive transistors 6 and 2 to perform a switching operation instead of the drive transistors 4 and 6, and sets the drive transistors 1, 4 and 5 to the non-conductive state.
[0073]
  In the period TW1 in which the W-phase current I3 is a discharge current having a substantially constant magnitude, the energized phase switching circuit 23 keeps the drive transistor 5 in a conductive state instead of the drive transistor 1. In addition, the energized phase switching circuit 23 causes the drive transistors 2 and 4 to perform a switching operation in place of the drive transistors 4 and 6, and sets the drive transistors 1, 3 and 6 to a non-conductive state.
[0074]
  The operation of the motor driving device in FIG. 1 during the periods TV2 and TW2 is the same as that during the period TU2 except for the following points. In other words, during the period TV2 in which the V-phase current I2 is a suction current having a substantially constant magnitude, the energized phase switching circuit 23 causes the drive transistor 4 to be continuously turned on instead of the drive transistor 2. Further, the energized phase switching circuit 23 causes the drive transistors 5 and 1 to perform a switching operation in place of the drive transistors 3 and 5, and sets the drive transistors 2, 3 and 6 to a non-conductive state.
[0075]
  In the period TW2 in which the W-phase current I3 is a suction current having a substantially constant magnitude, the energized phase switching circuit 23 keeps the drive transistor 6 in a conductive state instead of the drive transistor 2. In addition, the energized phase switching circuit 23 causes the drive transistors 1 and 3 to perform a switching operation instead of the drive transistors 3 and 5, and sets the drive transistors 2, 4, and 5 to a non-conductive state.
[0076]
  FIG. 10 is a block diagram showing another example of the configuration of the logic control circuit of FIG. The logic control circuit 140 of FIG. 10 is the logic control circuit 40 further including a delay circuit 47. A reference pulse PI is input to the delay circuit 47. The delay circuit 47 delays the inputted reference pulse PI by a predetermined time and outputs it to the set input of the RS flip-flop 42.
[0077]
  When the logic control circuit 140 shown in FIG. 10 is used instead of the logic control circuit 40 shown in FIG. 3, the RS flip-flop 41 is set and the control signal F1 changes to “H”. The control signal F2 changes to “H”. Thus, the control signals F1 and F2 do not change from “L” to “H” at the same time.
[0078]
  For example, in the period TU1, the driving transistor 6 is turned on and the W-phase current I3 starts to flow after a predetermined period from when the driving transistor 4 is turned on first and the V-phase current I2 starts to flow. For this reason, it is possible to avoid a situation in which switching noise generated when two-phase currents start to flow simultaneously is superimposed on the ground line, and the voltage of the current detection resistor 7 has already exceeded the target value. Further, the possibility that the RS flip-flop 42 malfunctions due to the switching noise of the driving transistor can be reduced. Note that the delay circuit 47 is not necessarily required if measures such as reducing the wiring resistance of the ground line are taken.
[0079]
  As described above, according to the motor driving apparatus of the present embodiment, the phase currents I1 to I3 of the motor 10 are controlled so as to have a substantially trapezoidal waveform having an amplitude corresponding to the torque command voltage TI as shown in FIG. Therefore, the change of the phase current at the time of switching the energized phase can be moderated.
[0080]
  In addition, when PWM control is performed on a three-phase current, usually three current detection resistors are required. However, the motor driving device of the present embodiment can control three-phase currents using one current detection resistor, and enables PWM control in which the magnitudes of the phase currents do not vary. Since the number of current detection resistors is small, the scale of the device can be reduced.
[0081]
  (Second Embodiment)
  FIG. 11 is a block diagram of a motor drive device according to the second embodiment of the present invention. The motor drive device of FIG. 11 is the same as the motor drive device of FIG. 1 except that the phase-specific torque signal generation circuit 30, the logic control circuit 40, and the comparator 51 are replaced by the phase-specific torque signal generation circuit 230 and the logic control. A circuit 240, a first comparator 52, and a second comparator 53 are provided. Since other components are the same as those described in the first embodiment, the same reference numerals are assigned and description thereof is omitted. The phase-specific torque signal generation circuit 230, the logic control circuit 240, and the comparators 52 and 53 constitute an energization period control unit 200.
[0082]
  In FIG. 11, the phase-specific torque signal generation circuit 230 is a target value of the current that flows through the current detection resistor 7 based on the position signal PS and the torque command voltage TI, similarly to the phase-specific torque signal generation circuit 30 of FIG. 3. A signal TS indicating a voltage corresponding to is generated. The phase-specific torque signal generation circuit 230 outputs the torque command voltage TI and the signal TS to the positive input terminals of the comparators 52 and 53, respectively. The torque command voltage TI may be input to the comparator 52 without going through the phase-specific torque signal generation circuit 230.
[0083]
  Voltages generated in the current detection resistor 7 (source potentials of the drive transistors 2, 4, 6) are input to the negative input terminals of the comparators 52, 53 as the motor current detection signal MC. The comparators 52 and 53 output the respective outputs CP1 and CP2 to the logic control circuit 240. Further, the reference pulse PI is input to the logic control circuit 240. The logic control circuit 240 generates switching operation control signals F1 and F2 that define a period during which the driving transistors 1 to 6 are turned on, and outputs the switching operation control signals F1 and F2 to the energized phase switching circuit 23.
[0084]
  FIG. 12 is a block diagram illustrating an example of the configuration of the energization period control unit 200 of FIG. The energization period control unit 200 includes a phase-specific torque signal generation circuit 230, a logic control circuit 240, and comparators 52 and 53. The phase-specific torque signal generation circuit 230 shown in FIG. 12 includes a both-edge differentiation circuit 31, a constant current source 32, a switch 33, a capacitor 34, and a level control circuit 35. The phase-specific torque signal generation circuit 230 generates the phase-specific torque signal shown in FIG. 3 except that the torque command voltage TI and the output TS of the level control circuit 35 shown in FIG. 4 are output to the comparators 52 and 53 as they are. This is the same as the circuit 30.
[0085]
  The logic control circuit 240 of FIG. 12 includes an RS flip-flop 41 as a first latch, an RS flip-flop 42 as a second latch, inverters 44 and 45, and a NAND gate 46. Inverters 44 and 45 and NAND gate 46 operate as logic circuit 49.
[0086]
  The operation of the logic control circuit 240 and the current flowing through the motor 10 will be described with reference to FIGS. The reference pulse PI is input to the set terminals of the RS flip-flops 41 and 42 in FIG. When the reference pulse PI falls, the RS flip-flops 41 and 42 are set, so that the control signals F1 and F2 both become “H”. When the control signal F1 is “H”, the output of the inverter 44 is “L” and the output of the NAND gate 46 is “H”. Therefore, regardless of the level of the output CP2 of the comparator 53, the RS flip-flop 42 Not reset.
[0087]
  Assume that it is currently within the period TU1 of FIG. When the control signals F1 and F2 are both “H”, the energized phase switching circuit 23 turns on the drive transistors 4 and 6 (first period T1), and the V phase flows through the V phase coil 12 and the W phase coil 13, respectively. Both the current I2 and the W-phase current I3 flow through the current detection resistor 7. A voltage proportional to the magnitude of the current flowing through the current detection resistor 7 is generated, and this voltage is input to the negative input terminals of the comparators 52 and 53 as the motor current detection signal MC.
[0088]
  When the motor current detection signal MC gradually increases and the voltage of the motor current detection signal MC reaches the voltage of the signal TI, the comparator 52 changes the output CP1 to “L”. Then, the RS flip-flop 41 is reset and its output is changed to “L”, so that the control signal F1 becomes “L”. Then, since the output of the inverter 44 becomes “H”, the RS flip-flop 42 is reset according to the level change of the output CP2 of the comparator 53.
[0089]
  Since the control signals F1 and F2 become “L” and “H”, respectively, the energized phase switching circuit 23 makes the drive transistor 4 non-conductive. The drive transistor 6 remains conductive (second period T2). At this time, since only the current flowing in the W-phase coil 13 flows in the current detection resistor 7, the current in the W-phase coil 13 can be detected without being affected by the current in the V-phase coil 12.
[0090]
  Since drive transistors 1 and 6 are still conductive, the current of W-phase coil 13 continues to increase, and the current flowing through current detection resistor 7 continues to increase. When the voltage of the motor current detection signal MC reaches the voltage of the signal TS output from the phase-specific torque signal generation circuit 230, the comparator 53 sets the output CP2 to “L”. Then, the output of the NAND gate 46 becomes “L”, the RS flip-flop 42 is reset, and the control signal F2 becomes “L”.
[0091]
  Since the control signals F1 and F2 both become “L”, the energized phase switching circuit 23 also turns off the drive transistor 6 (period T3).
[0092]
  As described above, the motor driving device of FIG. 11 can drive the motor 10 in the same manner as the motor driving device of FIG. The motor driving device of FIG. 11 can perform stable operation because the comparators 52 and 53 are unlikely to malfunction.
[0093]
  In the above embodiment, the motor driving device has been described as including the diodes 1D to 6D, but each of the driving transistors 1 to 6 may include a parasitic diode instead. That is, a diode may structurally exist in each of the driving transistors 1 to 6.
[0094]
  The driving transistors 1 to 6 may be transistors other than n-type MOS transistors.
[0095]
  Further, the case where the current detection resistor 7 is provided between the source of the lower arm side drive transistors 2, 4, 6 and the ground has been described, but between the power supply VCC and the drain of the upper arm side drive transistors 1, 3, 5. May include a current detection resistor.
[0096]
  Moreover, although the example controlled by the period corresponding to what divided the electrical angle 360 degrees of the motor 10 into 6 units was demonstrated, you may divide into 12 and switch an energized phase for every shorter period, for example.
[0097]
  Further, although the motor connection has been described as the Y connection, it may be a delta connection.
[0098]
  In addition, although the example in which the drive transistor of the phase whose current is to be reduced among the two-phase drive transistors that perform the switching operation is first made non-conductive has been described, the sawtooth wave that rises sharply and falls gently If the signal TS is used, the driving transistor of the phase whose current is to be increased can be operated in the same manner even if the driving transistor is turned off first.
[0099]
  Moreover, although the case where the phase of the three-phase phase current is set to the U phase, the V phase, and the W phase in order from the leading one has been described, in order to reverse the motor, the order of the W phase, the V phase, and the U phase is described. The same applies to the case.
[0100]
  Although the case of driving a three-phase motor has been described, the same applies to the case of driving a motor having four or more phases.
[0101]
  Further, although the case where position detection is performed using a Hall element has been described, it is not always necessary to use a Hall element. For example, a CR filter circuit is provided for each of the U-phase, V-phase, and W-phase to filter the harmonic components of the PWM drive current, and for each phase, the filter output and the midpoint potential of the motor coil are compared. Thus, the position of the rotor of the motor can be detected. However, when a malfunction caused by the harmonic component of the PWM drive current is taken into consideration, it is more advantageous to use a Hall element.
[0102]
【The invention's effect】
  According to the motor driving device of the present invention, it is possible to prevent the phase current from changing suddenly, so that it is possible to suppress the occurrence of motor vibration and noise during phase switching. In order to control the currents of a plurality of phases, normally only one current detection resistor, which is required in plural, is used, so the scale of the apparatus can be reduced.
[Brief description of the drawings]
FIG. 1 is a block diagram of a motor drive device according to a first embodiment of the present invention.
FIG. 2 is a graph showing a target waveform of each phase current of a motor.
FIG. 3 is a block diagram illustrating an example of a configuration of an energization period control unit in FIG. 1;
FIG. 4 is a graph showing signals related to a position detection circuit and a phase-specific torque signal generation circuit.
FIG. 5 is a graph showing input / output signals of the logic control circuit and the comparator of FIG. 1;
6 is a graph showing phase currents in the motor drive device of FIG. 1. FIG.
FIG. 7 is an explanatory diagram showing a path of a current flowing through a motor in a period T1.
FIG. 8 is an explanatory diagram showing a path of a current flowing through a motor in a period T2.
FIG. 9 is an explanatory diagram showing a path of a current flowing through the motor in a period T3.
10 is a block diagram showing another example of the configuration of the logic control circuit of FIG. 1. FIG.
FIG. 11 is a block diagram of a motor drive device according to a second embodiment of the present invention.
12 is a block diagram illustrating an example of a configuration of an energization period control unit in FIG. 11. FIG.
FIG. 13 is a block diagram of a conventional motor driving device using a peak current detection method.
14 is a graph showing a change with respect to time of each phase current of a motor driven by the motor driving device of FIG. 13; FIG.
15 is a graph showing the current detection resistance voltage and the V-phase and W-phase phase currents in the vicinity of time t = tz in FIG.
[Explanation of symbols]
1-3 Upper arm side drive transistor (upper arm side switching element)
4-6 Lower arm drive transistor (lower arm switching element)
1D-6D diode
7 Current detection resistor
10 Motor
11 U-phase coil
12 V-phase coil
13 W phase coil
21 Hall element circuit
22 Position detection circuit
23 Energized phase switching circuit
24 Pre-drive circuit
30,230 Phase-specific torque signal generation circuit
40, 140, 240 Logic control circuit
41 RS flip-flop (first latch)
42 RS flip-flop (second latch)
43, 47 delay circuit
49 Logic Circuit
51 comparator
52 First comparator
53 Second comparator
100, 200 energization period control unit

Claims (11)

A plurality of output circuits having an upper arm side switching element and a lower arm side switching element connected in series are provided, and a current is supplied to the motor from a connection point between the upper arm side switching element and the lower arm side switching element in each of the output circuits. A motor driving device for supplying
A current detection resistor connected in series with the plurality of output circuits and commonly connected to detect a current supplied to the plurality of output circuits;
A position detector that outputs a position signal corresponding to the position of the rotor of the motor;
One switching element in any one of the plurality of output circuits is selected in accordance with the position signal, and is turned on in a period corresponding to a predetermined electrical angle. In the case where the switching element is an element, the switching operation is performed on the lower arm side switching element in any of the remaining plurality of the output circuits, and when the switching element to be conducted is the lower arm side switching element, the remaining of the plurality of output circuits An energized phase switching circuit that causes the upper arm side switching element in any one of
In each of a plurality of periods divided by a period corresponding to the predetermined electrical angle, among the switching elements for performing the switching operation, a first period for conducting a plurality of switching elements and a conduction for the first period The energized phase switching is performed according to the input torque command signal and the voltage generated in the current detection resistor so that there is a second period in which any one of the plurality of switching elements is continuously conducted. A switching operation control signal for controlling the switching operation by the circuit is generated and provided with an energization period control unit for outputting ,
The energization period control unit
According to the torque command signal, the first target signal corresponding to the target value of the current to be passed through the current detection resistor in the first period, and the torque command signal and the position signal, A phase-specific torque signal generation circuit that alternately outputs a second target signal corresponding to a target value of a current to be passed through the current detection resistor in a second period;
A comparator that determines whether a voltage generated in the current detection resistor exceeds an output of the phase-specific torque signal generation circuit and outputs the result;
A motor drive device comprising: a logic control circuit that generates and outputs the switching operation control signal in accordance with a reference pulse that defines a cycle of the switching operation and an output of the comparator . The motor drive device according to claim 1 ,
Before Symbol logic control circuit,
When the comparator determines that the voltage generated in the current detection resistor exceeds the output of the phase-specific torque signal generation circuit for the first period, the first period ends, and the current detection resistor When it is determined that the generated voltage exceeds the output of the phase-specific torque signal generation circuit for the second period, the switching operation control signal is generated and output so as to end the second period. A motor drive device. In the motor drive device according to claim 2,
The logic control circuit is
A first latch set by the reference pulse and having the output of the comparator as a reset input;
A second latch set by the reference pulse;
A logic circuit that receives the output of the first latch and the output of the comparator as inputs and supplies the obtained output as a reset input to the second latch; and outputs of the first and second latches Is output as the switching operation control signal,
The first latch is
Reset when the output of the comparator indicates that the voltage across the current sensing resistor exceeds the first target signal;
The logic circuit is
When the output of the first latch indicates that the first latch is reset, the output of the comparator is output, indicating that the first latch is not reset. When the output of the comparator is not output,
The second latch is
Reset when the logic circuit outputs the output of the comparator and the output of the comparator indicates that the voltage across the current sense resistor exceeds the second target signal A motor drive device characterized by being a thing. In the motor drive device according to claim 3,
The logic control circuit is
A delay circuit for outputting the output of the first latch with a predetermined time delay;
The first latch is
The motor drive device characterized in that the output is given to the logic circuit via the delay circuit. A plurality of output circuits having an upper arm side switching element and a lower arm side switching element connected in series are provided, and a current is supplied to the motor from a connection point between the upper arm side switching element and the lower arm side switching element in each of the output circuits. A motor driving device for supplying
A current detection resistor connected in series with the plurality of output circuits and commonly connected to detect a current supplied to the plurality of output circuits;
A position detector that outputs a position signal corresponding to the position of the rotor of the motor;
One switching element in any one of the plurality of output circuits is selected in accordance with the position signal, and is turned on in a period corresponding to a predetermined electrical angle. In the case where the switching element is an element, the switching operation is performed on the lower arm side switching element in any of the remaining plurality of the output circuits, and when the switching element to be conducted is the lower arm side switching element, the remaining of the plurality of output circuits An energized phase switching circuit that causes the upper arm side switching element in any one of
In each of a plurality of periods divided by a period corresponding to the predetermined electrical angle, among the switching elements for performing the switching operation, a first period for conducting a plurality of switching elements and a conduction for the first period The energized phase switching is performed according to the input torque command signal and the voltage generated in the current detection resistor so that there is a second period in which any one of the plurality of switching elements is continuously conducted. A switching operation control signal for controlling the switching operation by the circuit is generated and provided with an energization period control unit for outputting,
The energization period control unit
According to the torque command signal, the first target signal corresponding to the target value of the current to be passed through the current detection resistor in the first period, and the torque command signal and the position signal, A phase-specific torque signal generation circuit that outputs a second target signal corresponding to a target value of a current to be passed through the current detection resistor in a second period;
A first comparator for determining whether a voltage generated in the current detection resistor exceeds the first target signal and outputting the result;
A second comparator for determining whether or not a voltage generated in the current detection resistor exceeds the second target signal and outputting the result;
Reference pulse that defines the period of the switching operation, and in accordance with the output of the first and second comparators, is shall a logic control circuit that generates and outputs the switching operation control signal
Motor driving apparatus according to claim and this. In the motor drive device according to claim 5,
The logic control circuit is
If the first comparator determines that the voltage generated in the current detection resistor exceeds the first target signal, the first period is ended, and the second comparator detects the current detection. If it is determined that the voltage generated in the resistor exceeds the second target signal, the switching operation control signal is generated and output so as to end the second period. A motor drive device. In the motor drive device according to claim 6 ,
The logic control circuit is
A first latch set by the reference pulse and having the output of the first comparator as a reset input;
A second latch set by the reference pulse;
A logic circuit that receives the output of the first latch and the output of the second comparator as inputs and provides the obtained output as a reset input to the second latch; and The output of the latch is output as the switching operation control signal,
The first latch is
Reset when the output of the first comparator indicates that the voltage across the current sensing resistor exceeds the first target signal;
The logic circuit is
When the output of the first latch indicates that the first latch is reset, the output of the second comparator is output, and the first latch is not reset. When it is shown, the output of the second comparator is not output,
The second latch is
The logic circuit outputs the output of the second comparator, and the output of the second comparator indicates that the voltage generated in the current detection resistor exceeds the second target signal. A motor driving device that is reset when the motor is in operation. In the motor drive device according to claim 1 or 5,
A motor driving apparatus characterized in that the period of the reference pulse is substantially constant. In the motor drive device according to claim 1 or 5,
The phase-specific torque signal generation circuit includes:
The voltage corresponding to the torque command signal is used as the first target signal, the period is a period corresponding to the predetermined electrical angle based on the position signal and the first target signal, and the peak value Generates a sawtooth wave substantially equal to the first target signal and uses it as the second target signal. A plurality of output circuits each having an upper arm side switching element and a lower arm side switching element connected in series are provided, and are connected in series and in common to the plurality of output circuits, and are supplied to the plurality of output circuits. A motor driving device that supplies a current to the motor from a connection point between the upper arm side switching element and the lower arm side switching element in each of the output circuits.
Obtaining a position signal according to the position of the rotor of the motor;
Selecting one switching element in any one of the plurality of output circuits according to the position signal, and conducting in a period corresponding to a predetermined electrical angle;
When the switching element to be conducted is an upper arm side switching element, the lower arm side switching element in any of the remaining plurality of the plurality of output circuits is caused to perform a switching operation, and the switching element to be conducted is a lower arm side switching element. If there is, the step of switching the upper arm side switching element in any of the remaining plurality of the plurality of output circuits,
It steps for the switching operation,
In each of a plurality of periods divided by a period corresponding to the predetermined electrical angle, among the switching elements for performing the switching operation, a first period for conducting a plurality of switching elements and a conduction for the first period And passing through the current detection resistor in the first period according to the input torque command signal so that there is a second period in which any one of the plurality of switching elements that have been made continues to be conducted. The first target signal corresponding to the target value of the power current, the first target signal corresponding to the target value of the current to be passed through the current detection resistor in the second period, obtained according to the torque command signal and the position signal. alternatively 2 of the target signal, as compared to the voltage generated in the current detecting resistor, according to the reference pulses defines the period of the result and the switching operation, before <br/> motor driving method is for controlling the switching operation. A plurality of output circuits each having an upper arm side switching element and a lower arm side switching element connected in series are provided, and are connected in series and in common to the plurality of output circuits, and are supplied to the plurality of output circuits. A motor driving device that supplies a current to the motor from a connection point between the upper arm side switching element and the lower arm side switching element in each of the output circuits,
Obtaining a position signal according to the position of the rotor of the motor;
Selecting one switching element in any one of the plurality of output circuits according to the position signal, and conducting in a period corresponding to a predetermined electrical angle;
When the switching element to be conducted is an upper arm side switching element, the lower arm side switching element in any of the remaining plurality of the plurality of output circuits is caused to perform a switching operation, and the switching element to be conducted is a lower arm side switching element. If there is, the step of switching the upper arm side switching element in any of the remaining plurality of the plurality of output circuits,
The step of performing the switching operation includes:
In each of a plurality of periods divided by a period corresponding to the predetermined electrical angle, among the switching elements for performing the switching operation, a first period for conducting a plurality of switching elements and a conduction for the first period And passing through the current detection resistor in the first period according to the input torque command signal so that there is a second period in which any one of the plurality of switching elements that have been made is continuously conducted. The first target signal corresponding to the target value of the power current, the first target signal corresponding to the target value of the current to be passed through the current detection resistor in the second period, determined according to the torque command signal and the position signal. 2 target signal is compared with the voltage generated in the current detection resistor, and according to the result and a reference pulse defining the period of the switching operation, the switch And controls the quenching operation
Motor drive method.

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