Control device

Abstract

To provide a control device capable of detecting an offset voltage with neither requiring any exclusive part for detecting the offset voltage, nor stopping a motor.SOLUTION: A control device 1 comprises an inverter circuit 10 including a plurality of switching elements SW1 to SW6 that comprise three upward-downward arms corresponding to respective phases of a three-phase motor 5 on a one-to-one basis. The control device 1 comprises a shunt resistance 4, a control circuit 2 for outputting a PWM drive signal to the inverter circuit, and an amplifier circuit 3. A motor control part 24 changes a pulse signal for controlling switching of a plurality of switching elements during periodical control. The motor control part 24 makes the switching element included in an arm located on a potential line side to which the shunt resistance 4 is connected by changing the pulse signal be in a state where no current flows. In this state, a current value acquisition part 22 acquires an off-set voltage converted by the shunt resistance 4.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The disclosure in this specification relates to a control device for controlling a motor. [Background technology]

[0002] Patent Document 1 discloses a current detection circuit that uses an input switch to set the set voltage input to the differential amplifier to 0 V in order to detect the offset voltage of the differential amplifier. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5072561 Summary of the Invention [Problem to be solved by the invention]

[0004] According to the current detection circuit of Patent Document 1, an input switch, which is a dedicated component, is required to detect the offset voltage.

[0005] An object of the disclosure of this specification is to provide a control device that does not require a dedicated component for detecting an offset voltage and that can detect an offset voltage without stopping a motor. [Means for solving the problem]

[0006] The multiple aspects disclosed in this specification employ different technical means to achieve their respective objectives. Furthermore, the reference symbols in parentheses in the claims and this section are merely examples showing the correspondence between specific means described in the embodiments below as one aspect, and do not limit the technical scope.

[0007] One of the disclosed control devices includes an inverter circuit (10) that includes a plurality of switching elements (SW1 to SW6) that constitute three upper and lower arms that correspond one-to-one to each phase of a three-phase motor (5), and outputs a drive voltage to the motor by switching the switching elements based on a PWM drive signal; a shunt resistor (4) provided between a ground potential line (10N) of the inverter circuit and ground, or between a high potential line (10P) of the inverter circuit and a power supply unit (6); a control circuit (2) that outputs a PWM drive signal to an inverter circuit; an amplifier circuit (3) that amplifies the voltage converted from the current by the shunt resistor and outputs the voltage to the control circuit; Equipped with The control circuit includes a current value acquisition unit (22) that calculates a current value based on a signal input via the amplifier circuit, an offset correction unit (23) that performs processing to cancel an offset voltage from the output voltage of the amplifier circuit, and a motor control unit (24) that controls the switching element to achieve a target rotation speed and performs periodic control of the motor. During periodic control, the motor control unit changes the pulse signal that controls the switching of the multiple switching elements to prevent current from flowing through the switching elements included in the arm located on the potential line side to which the shunt resistor is connected, and in this state, the current value acquisition unit acquires the offset voltage converted by the shunt resistor. death, During periodic control, if the timing at which the induced voltage from the motor generated in the non-energized phase of the motor overlaps with the average of the energized phase voltage is detected, the motor control unit shifts the timing and changes the pulse signal that controls the switching of the switching element. do. Another disclosed control device includes an inverter circuit (10) including a plurality of switching elements (SW1 to SW6) constituting three upper and lower arms corresponding one-to-one to each phase of a three-phase motor (5), and outputting a drive voltage to the motor by switching the switching elements based on a PWM drive signal; a shunt resistor (4) provided between a ground potential line (10N) of the inverter circuit and ground, or between a high potential line (10P) of the inverter circuit and a power supply unit (6); a control circuit (2) that outputs a PWM drive signal to an inverter circuit; an amplifier circuit (3) that amplifies the voltage converted from the current by the shunt resistor and outputs the voltage to the control circuit; Equipped with The control circuit includes a current value acquisition unit (22) that calculates a current value based on a signal input via the amplifier circuit, an offset correction unit (23) that performs processing to cancel an offset voltage from the output voltage of the amplifier circuit, and a motor control unit (24) that controls the switching element to achieve a target rotation speed and performs periodic control of the motor. During the periodic control, the motor control unit changes the pulse signal that controls the switching of the multiple switching elements to prevent current from flowing through the switching elements included in the arm located on the potential line side to which the shunt resistor is connected, and in this state the current value acquisition unit acquires the offset voltage converted by the shunt resistor; During periodic control, if a timing is detected at which the induced voltage from the motor generated in one of the three non-energized phases of the motor overlaps with the average of the energized phase voltages, the motor control unit changes the pulse signal that controls the switching of the switching element to deviate from the timing. Yet another disclosed control device includes an inverter circuit (10) including a plurality of switching elements (SW1 to SW6) constituting three upper and lower arms corresponding one-to-one to each phase of a three-phase motor (5), and outputting a drive voltage to the motor by switching the switching elements based on a PWM drive signal; a shunt resistor (4) provided between a ground potential line (10N) of the inverter circuit and ground, or between a high potential line (10P) of the inverter circuit and a power supply unit (6); a control circuit (2) that outputs a PWM drive signal to an inverter circuit; an amplifier circuit (3) that amplifies the voltage converted from the current by the shunt resistor and outputs the voltage to the control circuit; Equipped with The control circuit includes a current value acquisition unit (22) that calculates a current value based on a signal input via the amplifier circuit, an offset correction unit (23) that performs processing to cancel an offset voltage from the output voltage of the amplifier circuit, and a motor control unit (24) that controls the switching element to achieve a target rotation speed and performs periodic control of the motor. During the periodic control, the motor control unit changes the pulse signal that controls the switching of the multiple switching elements to prevent current from flowing through the switching elements included in the arm located on the potential line side to which the shunt resistor is connected, and in this state the current value acquisition unit acquires the offset voltage converted by the shunt resistor; During periodic control, if a trigger for offset correction is established and it is detected that the number of rotations of the motor has decreased by a predetermined number of rotations, the motor control unit changes the pulse signal that controls the switching of the switching element. Yet another disclosed control device includes an inverter circuit (10) including a plurality of switching elements (SW1 to SW6) constituting three upper and lower arms corresponding one-to-one to each phase of a three-phase motor (5), and outputting a drive voltage to the motor by switching the switching elements based on a PWM drive signal; a shunt resistor (4) provided between a ground potential line (10N) of the inverter circuit and ground, or between a high potential line (10P) of the inverter circuit and a power supply unit (6); a control circuit (2) that outputs a PWM drive signal to an inverter circuit; an amplifier circuit (3) that amplifies the voltage converted from the current by the shunt resistor and outputs the voltage to the control circuit; Equipped with The control circuit includes a current value acquisition unit (22) that calculates a current value based on a signal input via the amplifier circuit, an offset correction unit (23) that performs processing to cancel an offset voltage from the output voltage of the amplifier circuit, and a motor control unit (24) that controls the switching element to achieve a target rotation speed and performs periodic control of the motor. During the periodic control, the motor control unit changes the pulse signal that controls the switching of the multiple switching elements to prevent current from flowing through the switching elements included in the arm located on the potential line side to which the shunt resistor is connected, and in this state the current value acquisition unit acquires the offset voltage converted by the shunt resistor; During periodic control, if the motor control unit detects the timing at which the induced voltage from the motor generated in the non-energized phase of the motor's three phases overlaps with the average of the energized phase voltage, and then detects that the motor's rotation speed has decreased by a predetermined number of rotations, the motor control unit changes the pulse signal that controls the switching of the switching element.

[0008] According to this control device, a state in which no current flows through the shunt resistor can be temporarily created by changing the pulse signal during periodic control of the motor. By acquiring the offset voltage in this state, the offset voltage can be detected while the motor is rotating by inertia and not stopped. The offset correction unit cancels the detected offset voltage with high accuracy. This allows for highly accurate detection of the offset voltage and for returning to periodic control without stopping the motor. Therefore, the control device does not require a dedicated component for offset voltage detection and can detect the offset voltage without stopping the motor. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram illustrating an example of a configuration including a control device. [Figure 2] 10A and 10B are diagrams illustrating an example of switching when detecting a current value in a U-phase-V-phase current flow. [Figure 3] 10 is a timing chart showing switching when current is applied between the U phase and the V phase. [Figure 4] 10A and 10B are diagrams illustrating an example of switching during U-phase-V-phase current conduction. [Figure 5] 10A and 10B are diagrams illustrating an example of switching when an offset voltage is acquired during U-phase-V-phase current conduction. [Figure 6] 10A and 10B are diagrams illustrating an example of switching after an offset voltage is acquired when current is applied between a U phase and a V phase; [Figure 7] 4 is a flowchart showing a control process of the control device according to the first embodiment. [Figure 8] 10 is a flowchart showing a control process of a control device according to a second embodiment. [Figure 9] 10 is a flowchart showing a control process of a control device according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, several embodiments for carrying out the present disclosure will be described with reference to the drawings. In each embodiment, parts corresponding to matters described in the preceding embodiment will be assigned the same reference numerals, and duplicate descriptions may be omitted. In each embodiment, when only a part of the configuration is described, other previously described embodiments may be applied to the other parts of the configuration. In addition to combinations of parts that are specifically specified as being combinable in each embodiment, it is also possible to partially combine embodiments even if not specified, as long as there is no particular problem with the combination.

[0011] (First embodiment) A first embodiment, which is an example of a control device capable of achieving the object disclosed in this specification, will be described with reference to FIGS. 1 to 7. This control device is applicable to devices that require detection of current values, and in the example disclosed in this specification, it is applied to a device that controls the drive of a motor. This control device can be used in devices that control electric fuel pumps, air conditioner fans, etc. This control device can be used, for example, in vehicle devices that require detection of current values.

[0012] In this embodiment, as an example, the control device is applied to an electric fuel pump for a vehicle. The electric fuel pump is used as a hydraulic supply source that supplies oil to an oil supply destination, such as a hydraulic device mounted on a vehicle, such as a continuously variable transmission. The electric fuel pump is connected to a vehicle ECU, pumps up oil stored in an oil pan, applies hydraulic pressure, and supplies the oil to the oil supply destination.

[0013] The vehicle ECU is connected to various electronic components in the vehicle via a bus such as CAN (registered trademark). For example, when the engine is stopped due to an unloading stop, the vehicle ECU drives the electric fuel pump to supply oil to an oil supply destination. When the engine is stopped, the vehicle ECU sends a drive command to the electric fuel pump, including a target rotation speed of the motor 5, according to the temperature of the fuel. The electric fuel pump includes a pump unit, the motor 5, and a control device 1.

[0014] The pump unit is connected to the motor 5 and the oil supply destination. The pump unit is a pump driven by the motor 5. When driven by the motor 5, the pump unit pumps oil in the oil pan to the oil supply destination. The motor 5 includes a rotor having a permanent magnet and a stator on which coils 5Lu, 5Lv, and 5Lw corresponding to the three phases U, V, and W are wound in order in the direction of rotation of the rotor. The coils 5Lu, 5Lv, and 5Lw for each phase are each connected to the control device 1.

[0015] The control device 1 is connected to the vehicle ECU and the motor 5. The control device 1 controls the drive of the motor 5 based on a drive command output from the vehicle ECU. For example, the control device 1 performs feedback control of the motor 5 so that the motor 5 reaches a target value of a rotation speed command included in the drive command input from the vehicle ECU. The control device 1 performs field weakening control to increase motor torque when the motor 5 rotates at high speeds, and executes advance angle control to advance the timing at which current is applied to the motor 5 to the advance angle side.

[0016] The configuration of the control device 1 will be described with reference to Figures 1 and 2. As shown in Figure 1, the control device 1 includes a power supply unit 6, an inverter circuit 10, a control circuit 2, an amplifier circuit 3, and a shunt resistor 4. The power source to be converted by the inverter circuit 10 is a DC voltage supplied from the positive terminal of the power supply unit 6. The operating power source for the control circuit 2 is a DC voltage supplied from the positive terminal of the power supply unit 6. The operating power source for the amplifier circuit 3 is a DC voltage supplied from the positive terminal of the power supply unit 6 to a power terminal.

[0017] The power supply unit 6 is a storage battery mounted on the vehicle. The power supply unit 6 can be configured with a secondary battery such as a nickel-metal hydride battery or a lithium-ion battery. Instead of a secondary battery, the power supply unit 6 may be configured with an electric double layer capacitor.

[0018] The control device 1 includes a reactor 7 located at a position connecting the power supply unit 6 and the high-potential line 10P, and a plurality of capacitors 8. One terminal of the reactor 7 is connected to the DC power supply 300 and one capacitor 8, and the other terminal is connected to the two capacitors 8 and the high-potential line 10P. The reactor 7 is configured to be able to store and release electrical energy. The capacitor 8 is, for example, a filter capacitor that removes power supply noise or a smoothing capacitor.

[0019] The inverter circuit 10 has a plurality of switching elements SW. The inverter circuit 10 converts a power supply current into a phase current by controlling the on and off of the switching elements using PWM (Pulse Width Modulation). As shown in FIG. 2, the inverter circuit 10 has six switching elements SW1 to SW6. The inverter circuit 10 includes a switching circuit equipped with a plurality of switching elements SW. The inverter circuit 10 converts a power supply current into a phase current by switching the switching elements SW1 to SW6 on and off.

[0020] The inverter circuit 10 has three upper and lower arms corresponding one-to-one to the three phases. The three upper and lower arms are arranged in parallel with each other and connect a high potential line 10P and a ground potential line 10N. Each upper and lower arm includes two switching elements connected in series between the high potential line 10P and the ground potential line 10N.

[0021] The switching elements SW1 and SW2 are connected in series between the high potential line 10P and the ground potential line 10N and form an arm switch corresponding to the U phase. The connection point between the switching elements SW1 and SW2 is connected to one end of the coil 5Lu. The switching elements SW3 and SW4 are connected in series between the high potential line 10P and the ground potential line 10N and form an arm switch corresponding to the V phase. The connection point between the switching elements SW3 and SW4 is connected to one end of the coil 5Lv. The switching elements SW5 and SW6 are connected in series between the high potential line 10P and the ground potential line 10N and form an arm switch corresponding to the W phase. The connection point between the switching elements SW5 and SW6 is connected to one end of the coil 5Lw.

[0022] In this embodiment, the switching element SW is an FET (Field Effect Transistor), but is not limited to this. The switching element SW may be, for example, an IGBT (Insulated Gate Bipolar Transistor) or a BJT (Bipolar Junction Transistor). Each of the switching elements SW1 to SW6 is connected in parallel with a corresponding one of the freewheeling diodes D1 to D6. The gate terminal of each of the switching elements SW1 to SW6 is connected to the control circuit 2.

[0023] The shunt resistor 4 is provided between the ground side potential line 10N of the inverter circuit 10 and the ground. The ground side potential line 10N is connected to the circuit ground via the shunt resistor 4. In a modified example, the shunt resistor 4 may be provided between the high potential line 10P of the inverter circuit 10 and the power supply unit 6. The shunt resistor 4 constitutes one element of a current sensor for detecting the phase current.

[0024] The connection end between the ground side potential line 10N of the inverter circuit 10 and the shunt resistor 4 is connected to the input terminal of the amplifier circuit 3. The output terminal of the amplifier circuit 3 is connected to the motor current monitoring port of the control circuit 2.

[0025] The control circuit 2 generates a PWM drive signal in accordance with a rotation speed command input via a signal terminal from a vehicle ECU or the like, and outputs the PWM drive signal to the inverter circuit 10. As a result, in the inverter circuit 10, the switching element SW is driven, and a three-phase AC voltage is generated from the applied DC voltage and supplied to the motor 5.

[0026] The motor current value supplied to the motor 5 is converted into a voltage by the shunt resistor 4, amplified by the amplifier circuit 3 with a predetermined gain, and input to the control circuit 2. The control circuit 2 performs the operation according to this embodiment when a detection voltage corresponding to the motor current value detected by the amplifier circuit 3 is input. The control circuit 2 generates a rotation pulse signal for the motor 5 using the output voltage of the amplifier circuit 3, the DC voltage applied to the inverter circuit 10, a rotation speed command, etc.

[0027] The output voltage of the amplifier circuit 3 also contains an offset voltage. This offset voltage can cause errors in motor control. This error factor can impair the accuracy of detecting the motor current value. If highly accurate current value detection is required, a highly accurate operational amplifier is required, which can increase the cost of the device. Furthermore, if dedicated components are used to perform highly accurate current value detection, the cost of the device will also increase. For this reason, the control device 1 disclosed in this specification does not require dedicated components for offset voltage detection, and provides a device that can detect the offset voltage while the motor 5 is operating.

[0028] The control circuit 2 functions as a device that detects the motor current value. The control circuit 2 includes an A / D converter 21, a current value acquisition unit 22, an offset correction unit 23, and a motor control unit 24. The motor control unit 24, the current value acquisition unit 22, and the offset correction unit 23 can be realized, for example, by the CPU of a microcomputer executing a program in a storage device such as a ROM.

[0029] The control circuit 2 can be realized by a configuration including at least one processor. For example, the control circuit 2 can be realized by a computer including a processor, nonvolatile memory, RAM, I / O, and communication lines connecting these components. The nonvolatile memory stores a program for operating a general-purpose computer as a motor control device. The processor executes the program stored in the nonvolatile memory while utilizing the temporary storage function of the RAM. By executing this processor, the control circuit 2 operates as a motor control unit 24, a current value acquisition unit 22, and an offset correction unit 23. Execution of these operations means that a method corresponding to the program is being executed.

[0030] The motor control unit 24 controls the motor 5 by controlling the drive of the inverter circuit 10 in response to a drive command from the vehicle ECU or the like. At this time, the motor control unit 24 applies a gate signal to the gate electrode of each of the switching elements SW1 to SW6 of the inverter circuit 10 so as to satisfy the target rotation speed input as a rotation speed command. The motor control unit 24 performs periodic control by controlling the ON / OFF of the switching elements SW1 to SW6 so as to satisfy the PWM drive signal in accordance with the command from the vehicle ECU or the like. The motor control unit 24 performs periodic control by changing the duty of the PWM drive signal in accordance with the rotation speed and varying the rotation pulse signal it outputs.

[0031] The amplifier circuit 3 includes, for example, an operational amplifier (op-amp). The operational amplifier has a non-inverting input terminal, an inverting input terminal, and one output terminal. The non-inverting input terminal of the operational amplifier is electrically connected to the high potential side of the shunt resistor 4, and the inverting input terminal is electrically connected to the low potential side, which is the ground side, of the shunt resistor 4. The output terminal of the operational amplifier is electrically connected to the A / D converter 21. The operational amplifier constitutes one element of a current sensor for detecting phase currents.

[0032] The operational amplifier amplifies the voltage difference occurring across the shunt resistor 4 and outputs the amplified voltage difference to the A / D converter 21. The A / D converter 21 converts the analog signal output from the operational amplifier into a digital signal and outputs the digital signal to the current value acquiring unit 22. The current value acquiring unit 22 calculates the phase current based on the output signal from the A / D converter 21 and generates phase current information.

[0033] The control circuit 2 controls the switching element SW to a predetermined state, thereby capturing the output voltage of the amplifier circuit 3 while the motor 5 coasts without stopping. The current value acquisition unit 22 sets the acquired voltage value as an offset voltage. The offset correction unit 23 then performs a calculation to cancel the offset voltage from the output voltage of the amplifier circuit 3, thereby determining a highly accurate motor current value. In this way, the control circuit 2 can absorb errors in the amplifier circuit 3 and accurately detect the motor current value, thereby outputting even more accurate current information.

[0034] 2 to 7, the operation of the control circuit 2 for detecting a current value in this embodiment will be specifically described below. In this embodiment, as a representative example, the timing for detecting a current value, the trigger for offset correction, and the timing for acquiring an offset voltage will be described with reference to the drawings for the case where current is applied to the U phase and the V phase.

[0035] Figure 2 shows an example of switching when detecting current values ​​when the U and V phases are energized. Figure 3 is a timing chart showing the switching of SW1 to SW4 and changes in Ish when the U and V phases are energized. In Figure 3, the horizontal axis represents time T. Ish is the value of the current flowing through shunt resistor 4.

[0036] The motor control unit 24 controls the switching elements SW of the inverter circuit 10 to generate a PWM drive signal as shown in FIG. 3. In periodic control when current is applied to the U and V phases, the motor control unit 24 generates a PWM drive signal that repeats one cycle of signals up to time T2. In one cycle of periodic control, SW1 and SW4 are ON until time T1, SW2 and SW3 are OFF, and from T1 to T2, SW1 is switched OFF and SW2 is switched ON. During periodic control, the switch control up to T1 and the switch control from T1 to T2 are repeated. In addition, SW5, not shown in FIG. 3, are controlled to be OFF.

[0037] In Figure 2, the current flow is indicated by dashed arrows. During switch control up to T1, as shown in Figure 2, current flows from power supply unit 6 through SW1, coil 5Lu, coil 5Lv, and SW4 in that order, and then flows into shunt resistor 4. At this time, Ish, the current value flowing through shunt resistor 4, increases and peaks at T1, as shown in Figure 3. The current detection timing for periodic control is the time until T1 is reached. In Figure 4, the current flow is indicated by dashed arrows. During switch control from T1 to T2, as shown in Figure 4, current circulates through SW2, coil 5Lu, coil 5Lv, and SW4. At this time, Ish, the current value flowing through shunt resistor 4, decreases and reaches its lowest value at T2, as shown in Figure 3.

[0038] In the periodic control, the PWM control for one cycle up to T2 described above is repeated. If a trigger for offset correction is established during the periodic control, the control circuit 2 performs a process to acquire the offset voltage. If a trigger for offset correction is established during the periodic control, the following switch control is performed. FIG. 3 shows an example in which the trigger for offset correction is established and the control circuit switches to switch control for acquiring the offset voltage at T2. The control circuit 2 determines that the trigger for offset correction is established every time a predetermined time has elapsed. The control circuit 2 may also determine that the trigger for offset correction is established when the power is turned on. The control circuit 2 may also determine that the trigger for offset correction is established when the ambient temperature exceeds a threshold value. The control circuit 2 may also determine that the trigger for offset correction is established when the rotation speed of the motor 5 exceeds a reference value.

[0039] When the offset correction trigger is established, the control circuit 2 performs a control different from the regular control from time T2 to time T3 to execute the process of canceling the offset voltage. From time T2 to time T3, control is performed to switch SW3 ON and SW4 OFF. With this switching control, from time T2 to T3, as shown in FIG. 5, current circulates through SW3, SW1, coil 5Lu, and coil 5Lv.

[0040] Figure 5 shows an example of switching during offset voltage detection when the U and V phases are energized. In Figure 5, the current flow is indicated by dashed arrows. As shown in Figure 3, Ish, the current value flowing through shunt resistor 4, remains at its minimum or zero from T2 to T3. Control circuit 2 detects the offset voltage between T2 and T3. By switching SW3 ON and SW4 OFF at T2, control circuit 2 creates a current flow that bypasses the shunt resistor, allowing motor 5 to rotate by inertia. Therefore, control circuit 2 can obtain the offset voltage when Ish is at its minimum or zero without stopping motor 5 rotation.

[0041] Next, from time T3 to time T4, control circuit 2 performs the same switch control as from T1 to T2, and returns the PWM drive signal to the periodic control pattern. In Figure 6, the current flow is indicated by dashed arrows. During the switch control from T3 to T4, as shown in Figure 6, current flows circulating through SW2, coil 5Lu, coil 5Lv, and SW4, similar to the flow shown in Figure 4. Ish, the current value flowing through shunt resistor 4, remains at its minimum value or zero from T3 to T4, as shown in Figure 3.

[0042] From time T4 to time T6, the control circuit 2 performs the same switch control as that performed up to time T2 of the periodic control, as described above. The switch control from time T4 to time T6 sequentially forms the current flow shown in Figure 2 and the current flow shown in Figure 4. At this time, Ish, which is the value of the current flowing through the shunt resistor 4, changes in the same way as it did up to time T2, as shown in Figure 3.

[0043] The current value detection timing, offset correction trigger, and offset voltage acquisition timing described above with reference to FIGS. 2 to 6 will now be described based on the processing shown in FIG. 7. FIG. 7 is a flowchart showing the control processing related to offset voltage detection by the control device 1. The control processing shown in FIG. 7 is started when the ignition switch or power switch of the vehicle is turned on. The control circuit 2 executes the periodic control described above in step S100. During the periodic control, the control circuit 2 determines in step S110 whether the offset correction trigger described above has been established. If the offset correction trigger has not been established in step S110, the process returns to step S100 and the periodic control continues. If it is determined that the offset correction trigger has been established, the control circuit 2 executes the offset voltage detection processing in steps S120 to S140.

[0044] In step S120, a process is performed to change the PWM control pattern from the periodic control pattern. In step S120, the motor control unit 24 controls the switching element SW to execute a process to switch to a PWM drive signal such as that between T2 and T3 in FIG. 3. In this process, a step section of the pulse signal in which no current flows through the shunt resistor 4 is formed, and the motor 5 continues to rotate by inertia. In this state, in step S130, the A / D converter 21 converts the analog signal output from the operational amplifier into a digital signal and outputs it to the current value acquisition unit 22. Furthermore, the current value acquisition unit 22 calculates and acquires current information corresponding to the offset voltage based on the output signal.

[0045] In step S140, the control circuit 2 executes a process of recording and storing current information corresponding to the offset voltage in a storage device such as RAM. Then, in step S150, the control circuit 2 executes a switching process of returning the PWM drive signal to the periodic control pattern, as shown between T3 and T4 in FIG. 3. After the process of step S150, the process returns to step S100 and continues to perform periodic control. The stored current information is used when the offset correction unit 23 performs calculations to cancel the offset voltage, contributing to highly accurate calculation of the motor current value.

[0046] The following describes the effects of the control device 1 of the first embodiment. The control device 1 includes an inverter circuit 10 that outputs a drive voltage to a motor 5 by switching switching elements based on a PWM drive signal, and a shunt resistor 4. The inverter circuit 10 includes multiple switching elements that form three upper and lower arms that correspond one-to-one to each phase of the three-phase motor 5. The shunt resistor 4 is provided between a ground-side potential line 10N of the inverter circuit 10 and ground, or between a high-potential line 10P and a power supply unit 6. The control device 1 includes a control circuit 2 and an amplifier circuit 3 that amplifies a voltage converted from a current by the shunt resistor 4 and outputs the voltage to the control circuit 2. The control circuit 2 includes a current value acquisition unit 22 that calculates a current value based on a signal input via the amplifier circuit 3, an offset correction unit 23, and a motor control unit 24. The offset correction unit 23 performs processing to cancel an offset voltage from the output voltage of the amplifier circuit 3.

[0047] During periodic control, the motor control unit 24 changes the pulse signals that control the switching of the multiple switching elements. This change process stops current from flowing through the switching elements included in the arm located on the potential line side to which the shunt resistor 4 is connected. In this state, the current value acquisition unit 22 acquires the offset voltage converted by the shunt resistor 4.

[0048] According to this control device 1, a state in which no current flows through the shunt resistor 4 can be temporarily provided by changing the pulse signal during periodic control of the motor 5. By acquiring the offset voltage in this state, the offset voltage can be detected while the motor 5 is rotating by inertia and not stopped. The control device 1 can detect the offset voltage with high accuracy and return to periodic control without stopping the motor 5. The offset correction unit 23 can perform processing to cancel the detected offset voltage with high accuracy. The control device 1 does not require a dedicated component for offset voltage detection and can detect the offset voltage without stopping the motor 5.

[0049] The control of the control device 1 is also useful in motor control methods in which positive and negative Ish constantly flow, such as balanced drive. The control of the control device 1 allows the motor 5 to coast while a current path is secured in the inverter circuit 10. This allows the coasting rotation time to be extended, contributing to obtaining the offset voltage when Ish is zero.

[0050] (Second embodiment) The second embodiment will be described with reference to Fig. 8. The second embodiment differs from the first embodiment in the flowchart showing the control process related to offset voltage detection. The configurations, actions, and effects of the second embodiment that are not specifically described are the same as those of the first embodiment, and only the differences will be described below.

[0051] The control process shown in FIG. 8 differs from the control process of the first embodiment in that a determination process in step S112 is executed after a YES determination in step S110. In step S112, the control circuit 2 determines whether or not it has detected a timing at which the induced voltage from the motor 5, generated in a non-energized phase among the three phases, overlaps with the average of the energized phase voltages. This timing is also referred to as "zero-cross timing" in this specification. This embodiment discloses a case where the U phase and V phase are energized and the W phase is not energized. Therefore, the non-energized phase is the W phase, and the average of the energized phase voltages is the average of the U phase voltage and the V phase voltage. If a zero-cross timing is not detected in step S112, the process returns to step S100 and continues to perform periodic control.

[0052] When a zero-crossing timing is detected in step S112, the control circuit 2 performs an offset voltage detection process in steps S120 to S140. If the PWM control pattern is changed in step S120 at the zero-crossing timing, there is a concern that the average energized phase voltage will not be an appropriate value. To avoid this situation, it is desirable to perform the offset voltage detection process at a time other than the zero-crossing timing. The control process of the second embodiment can provide desirable control in which the average energized phase voltage approaches half the battery voltage.

[0053] In the control process of the second embodiment, the offset voltage detection process is performed when the offset correction condition is satisfied and at a timing other than a zero-crossing timing. Furthermore, in the control process of the second embodiment, the offset voltage detection process is preferably performed when the offset correction condition is satisfied and immediately after a zero-crossing timing. That is, when a timing is detected during periodic control at which the induced voltage from the motor generated in the non-energized phase overlaps with the average of the energized phase voltage, the pulse signal is shifted from this timing.

[0054] In this embodiment, a case where the U and V phases are energized and the W phase is not energized is described as a representative example, and therefore the process of step S112 is merely an example and is not intended to be limiting. In other words, the process of step S112 can also be applied to a case where the U and W phases are energized and the V phase is not energized, or a case where the V and W phases are energized and the U phase is not energized.

[0055] (Third embodiment) The third embodiment will be described with reference to Fig. 9. The third embodiment differs from the second embodiment in the flowchart showing the control process related to offset voltage detection. The configurations, actions, and effects of the third embodiment that are not specifically described are the same as those of the above-described embodiments, and only the differences will be described below.

[0056] 9 differs from the control process of the second embodiment in that after a YES determination is made in step S112, a determination process in step S114 is executed. In step S114, the control circuit 2 determines whether the rotation speed of the motor 5 has decreased by a predetermined instructed rotation speed. If the rotation speed of the motor 5 has not decreased by the instructed rotation speed in step S114, the process returns to step S100, and periodic control continues.

[0057] If it is detected in step S114 that the rotation speed of the motor 5 has decreased by the instructed rotation speed, the control circuit 2 performs steps S120 to S140 to detect the offset voltage. According to the control described in the specification, the load on the motor 5 during inertial rotation of the motor 5 can be reduced and then the current flowing through the shunt resistor 4 can be cut. However, because the load on the motor 5 cannot be reduced to zero, the rotation speed of the motor 5 decreases over time. According to the control process of the third embodiment, the offset voltage detection process is performed at the timing when the rotation speed of the motor 5 has decreased by the instructed rotation speed. This avoids the disadvantage of the rotation speed of the motor 5 decreasing during the offset voltage detection process.

[0058] When an offset correction trigger is satisfied during periodic control and it is detected that the rotation speed of the motor has decreased by a predetermined number of rotations, the motor control unit 24 changes the pulse signal. When it is detected during periodic control that the rotation speed of the motor has decreased by a predetermined number of rotations after detecting the zero-cross timing of S112, the motor control unit 24 changes the pulse signal. In the control process of the third embodiment, the offset voltage detection process is performed after the offset correction condition is satisfied and the rotation speed of the motor 5 has decreased by the specified number of rotations. In this control process, it is preferable that the offset voltage detection process is performed when the offset correction condition is satisfied and after the zero-cross timing and the rotation speed has decreased by the specified number of rotations.

[0059] (Other embodiments) The disclosure of this specification is not limited to the exemplified embodiments. The disclosure encompasses the exemplified embodiments and modifications thereto by those skilled in the art. For example, the disclosure is not limited to the combinations of parts and elements shown in the embodiments, and various modifications can be made. The disclosure can be implemented in various combinations. The disclosure can have additional parts that can be added to the embodiments. The disclosure encompasses the omission of parts and elements from the embodiments. The disclosure encompasses the substitution or combination of parts and elements between one embodiment and another embodiment. The disclosed technical scope is not limited to the description of the embodiments. The disclosed technical scope is defined by the claims, and should be interpreted as including all modifications within the meaning and scope of the claims.

[0060] In the above-described embodiment, the offset voltage acquisition timing and the like have been described using an example in which current is applied to the U and V phases. The description of the offset voltage acquisition timing and the like with reference to FIGS. 2 to 7 can also be applied to cases in which current is applied to the other three phases. When current is applied to the U and W phases, SW1 and SW5 are controlled to be ON and SW2 and SW6 are controlled to be OFF when acquiring the offset voltage. When current is applied to the V and W phases, SW3 and SW5 are controlled to be ON and SW4 and SW6 are controlled to be OFF when acquiring the offset voltage.

[0061] In the embodiment of this specification, an example has been described in which the control device 1 is applied to an electric fuel pump for a vehicle, but the control device 1 is not limited to this application example.

[0062] The apparatus and methods described herein may be implemented by a special-purpose computer comprising a processor programmed to perform one or more functions embodied in a computer program. Alternatively, the apparatus and methods described herein may be implemented by special-purpose hardware logic circuitry. Alternatively, the apparatus and methods described herein may be implemented by one or more special-purpose computers comprising a processor executing a computer program in combination with one or more hardware logic circuits. Furthermore, the computer program may be stored as instructions executed by a computer on a computer-readable non-transitory storage medium. [Explanation of symbols]

[0063] 2...Control circuit, 3...Amplification circuit, 4...Shunt resistor, 5...Motor, 6...Power supply unit, 10... inverter circuit; 10P... high potential line; 10N... ground potential line; 22...current value acquisition unit, 23...offset correction unit, 24...motor control unit

Claims

1. An inverter circuit (10) including a plurality of switching elements (SW1 to SW6) constituting three upper and lower arms corresponding one-to-one to each phase of a three-phase motor (5), and outputting a drive voltage to the motor by switching the switching elements based on a PWM drive signal; a shunt resistor (4) provided between a ground side potential line (10N) of the inverter circuit and ground, or between a high potential line (10P) of the inverter circuit and a power supply unit (6); a control circuit (2) that outputs a PWM drive signal to the inverter circuit; an amplifier circuit (3) that amplifies the voltage converted from the current by the shunt resistor and outputs the amplified voltage to the control circuit; Equipped with The control circuit includes a current value acquisition unit (22) that calculates a current value based on a signal input via the amplifier circuit, an offset correction unit (23) that performs processing to cancel an offset voltage from the output voltage of the amplifier circuit, and a motor control unit (24) that controls the switching element to achieve a target rotation speed and performs periodic control of the motor, During the periodic control, the motor control unit changes a pulse signal that controls switching of the plurality of switching elements to prevent current from flowing through the switching elements included in an arm located on a potential line side to which the shunt resistor is connected, and in this state, the current value acquisition unit acquires the offset voltage converted by the shunt resistor; When a trigger for offset correction is established during the periodic control, the motor control unit changes a pulse signal that controls switching of the switching element.

2. The control device according to claim 1 , wherein when the rotational speed of the motor exceeds a reference value during the periodic control, the motor control unit changes the pulse signal that controls the switching of the switching element.

3. An inverter circuit (10) including a plurality of switching elements (SW1 to SW6) constituting three upper and lower arms corresponding one-to-one to each phase of a three-phase motor (5), and outputting a drive voltage to the motor by switching the switching elements based on a PWM drive signal; a shunt resistor (4) provided between a ground side potential line (10N) of the inverter circuit and ground, or between a high potential line (10P) of the inverter circuit and a power supply unit (6); a control circuit (2) that outputs a PWM drive signal to the inverter circuit; an amplifier circuit (3) that amplifies the voltage converted from the current by the shunt resistor and outputs the amplified voltage to the control circuit; Equipped with The control circuit includes a current value acquisition unit (22) that calculates a current value based on a signal input via the amplifier circuit, an offset correction unit (23) that performs processing to cancel an offset voltage from the output voltage of the amplifier circuit, and a motor control unit (24) that controls the switching element to achieve a target rotation speed and performs periodic control of the motor, During the periodic control, the motor control unit changes a pulse signal that controls switching of the plurality of switching elements to prevent current from flowing through the switching elements included in an arm located on a potential line side to which the shunt resistor is connected, and in this state, the current value acquisition unit acquires the offset voltage converted by the shunt resistor; During the periodic control, when the timing at which the induced voltage from the motor generated in a non-energized phase of the three phases of the motor overlaps with the average of the energized phase voltages is detected, the motor control unit changes the pulse signal that controls the switching of the switching element to deviate from the timing.

4. An inverter circuit (10) including a plurality of switching elements (SW1 to SW6) constituting three upper and lower arms corresponding one-to-one to each phase of a three-phase motor (5), and outputting a drive voltage to the motor by switching the switching elements based on a PWM drive signal; a shunt resistor (4) provided between a ground side potential line (10N) of the inverter circuit and ground, or between a high potential line (10P) of the inverter circuit and a power supply unit (6); a control circuit (2) that outputs a PWM drive signal to the inverter circuit; an amplifier circuit (3) that amplifies the voltage converted from the current by the shunt resistor and outputs the amplified voltage to the control circuit; Equipped with The control circuit includes a current value acquisition unit (22) that calculates a current value based on a signal input via the amplifier circuit, an offset correction unit (23) that performs processing to cancel an offset voltage from the output voltage of the amplifier circuit, and a motor control unit (24) that controls the switching element to achieve a target rotation speed and performs periodic control of the motor, During the periodic control, the motor control unit changes a pulse signal that controls switching of the plurality of switching elements to prevent current from flowing through the switching elements included in an arm located on a potential line side to which the shunt resistor is connected, and in this state, the current value acquisition unit acquires the offset voltage converted by the shunt resistor; A control device in which, when it is detected during the periodic control that an offset correction trigger is established and the number of rotations of the motor has decreased by a predetermined number of rotations, the motor control unit changes the pulse signal that controls the switching of the switching element.

5. An inverter circuit (10) including a plurality of switching elements (SW1 to SW6) constituting three upper and lower arms corresponding one-to-one to each phase of a three-phase motor (5), and outputting a drive voltage to the motor by switching the switching elements based on a PWM drive signal; a shunt resistor (4) provided between a ground side potential line (10N) of the inverter circuit and ground, or between a high potential line (10P) of the inverter circuit and a power supply unit (6); a control circuit (2) that outputs a PWM drive signal to the inverter circuit; an amplifier circuit (3) that amplifies the voltage converted from the current by the shunt resistor and outputs the amplified voltage to the control circuit; Equipped with The control circuit includes a current value acquisition unit (22) that calculates a current value based on a signal input via the amplifier circuit, an offset correction unit (23) that performs processing to cancel an offset voltage from the output voltage of the amplifier circuit, and a motor control unit (24) that controls the switching element to achieve a target rotation speed and performs periodic control of the motor, During the periodic control, the motor control unit changes a pulse signal that controls switching of the plurality of switching elements to prevent current from flowing through the switching elements included in an arm located on a potential line side to which the shunt resistor is connected, and in this state, the current value acquisition unit acquires the offset voltage converted by the shunt resistor; During the periodic control, if the motor control unit detects a timing at which an induced voltage from the motor generated in a non-energized phase of the three phases of the motor overlaps with an average of the energized phase voltages, and then detects that the rotation speed of the motor has decreased by a predetermined number of rotations, the motor control unit changes the pulse signal that controls the switching of the switching element.

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