Semiconductor device and motor control device

Abstract

The dead time period is set appropriately to suppress the generation of through-currents. [Solution] This semiconductor device includes a timer counter that generates a periodic waveform according to the output of a timer, an operation setting unit that sets the operation determined by the periodic waveform for each cycle, a dead time period register that registers the dead time period for each cycle according to the setting in the operation setting unit, a dead time minimum value register that registers the minimum value of the dead time, a comparison circuit that compares the dead time period and the minimum value, and an error signal output circuit that outputs an error signal according to the output of the comparison circuit.

Description

Technical Field

[0001] The present invention relates to a semiconductor device and a motor control device.

Background Art

[0002] In order to control a three-phase motor, a microcomputer equipped with a PWM (Pulse Wave Modulation) control output device is widely used. For the control of a three-phase motor, three-phase outputs of a U-phase, a V-phase, and a W-phase are used. The motor is connected to a semiconductor circuit including a pair of series circuits of a P-type MOSFET and an N-type MOSFET, and control by the microcomputer is executed so that the P-type MOSFET and the N-type MOSFET are alternately in a conductive state.

[0003] In order to control a three-phase motor with high precision, it is necessary to switch the conduction signal of the P-type MOSFET and the conduction signal of the N-type MOSFET with high precision and finely control the ON / OFF periods of the P-type MOSFET and the N-type MOSFET.

[0004] However, due to the delay based on the wiring of the motor connected to the microcomputer and the variation in its temperature characteristics, etc., the P-type MOSFET and the N-type MOSFET may simultaneously turn on, resulting in a through-current flowing through the semiconductor circuit, which may cause excessive heat generation and disconnection of the wiring. It is necessary to avoid the occurrence of such a through-current.

[0005] In order to prevent the P-type MOSFET and the N-type MOSFET from simultaneously turning on, it is generally performed to set a dead time period in the microcomputer. The dead time period is a period during which both the P-type MOSFET and the N-type MOSFET of the semiconductor circuit are OFF, and it is a period for suppressing the occurrence of the above-mentioned through-current.

[0006] In motor control using a microcontroller, it is common practice to calculate the dead time period using software executed within the microcontroller. The software utilizes the microcontroller's timer to perform PWM waveform calculations at regular intervals and outputs the result to the semiconductor circuit for motor control. The dead time period is calculated during the PWM waveform calculation, and the result is stored in a dead time period register. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2013-81114

[0008] [overview] However, due to bugs or other issues in the software, it may not be possible to ensure the specified dead time period. In such cases, the P-type MOSFET and N-type MOSFET in the semiconductor circuit may turn ON simultaneously, causing a through-current. This through-current may lead to unnecessary heat generation and abnormal noise in the motor.

[0009] This disclosure aims to provide a motor control device that can appropriately set the dead time period and suppress the generation of through-current, taking the above circumstances into account.

[0010] To solve the above problems, the semiconductor device of this disclosure includes a timer counter that generates a periodic waveform according to the output of a timer, an operation setting unit that sets an operation determined by the periodic waveform for each cycle, a dead time period register that registers the dead time period for each cycle according to the setting in the operation setting unit, a dead time minimum value register that registers the minimum value of the dead time, a comparison circuit that compares the dead time period and the minimum value, and an error signal output circuit that outputs an error signal according to the output of the comparison circuit.

[0011] According to this disclosure, it is possible to provide a motor control device that can appropriately set the dead time period and suppress the generation of through-current. [Brief explanation of the drawing]

[0012] [Figure 1] Figure 1 is a block diagram illustrating the motor control device 1 according to an embodiment. [Figure 2] Figure 2 is a timing chart illustrating the operation of the motor control device 1 according to the embodiment. [Figure 3] Figure 3 is a block diagram illustrating a conventional motor control device 1c. [Figure 4] Figure 4 is a timing chart illustrating the operation of the conventional motor control device 1c.

[0013] [Detailed explanation] This embodiment will be described below with reference to the attached drawings. In the attached drawings, functionally identical elements may be indicated by the same number. The attached drawings show embodiments and implementation examples in accordance with the principles of this disclosure, but they are for the purpose of understanding this disclosure and are not to be used in any way to restrict the interpretation of this disclosure. The descriptions in this specification are merely typical examples and do not limit the claims or applications of this disclosure in any way.

[0014] While this embodiment is described in sufficient detail for those skilled in the art to implement the disclosure, it is important to understand that other implementations and forms are possible, and that the configuration and structure can be modified and various elements replaced without departing from the scope and spirit of the technical idea of ​​this disclosure. Therefore, the following description should not be construed as limiting to this.

[0015] The motor control device 1 according to an embodiment will be described with reference to the block diagram in Figure 1. This motor control device 1 is configured to include a microcomputer (MPC) 100 and an FET circuit (semiconductor circuit) 200 that generates a three-phase drive voltage to drive the motor 300 according to calculations performed by the microcomputer 100. The FET circuit 200 includes multiple series circuits of P-type MOSFETs and N-type MOSFETs (not shown), and drives the motor 300 by alternately turning the P-type MOSFETs and N-type MOSFETs (not shown) into a conductive state (ON).

[0016] The microcontroller 100 includes a CPU (Central Processing Unit) (not shown) and various memories, and outputs control signals to control the ON / OFF state of the P-type MOSFETs and N-type MOSFETs of the FET circuit 200. The microcontroller 100 includes a software execution unit 110 that executes software stored in memory, and a control signal generation unit 120 that generates control signals according to software instructions, sets a dead time period, and registers and outputs an error signal if the set dead time period falls below a minimum value.

[0017] The software execution unit 110 sets an operation cycle determined by the generated periodic waveform, and for each operation cycle, it performs a next-cycle calculation to calculate the operation parameters for the next cycle during the current operation cycle. In other words, the software execution unit 110 functions as an operation setting unit that sets the operation of the motor 300 for each cycle.

[0018] The control signal generation unit 120 further includes a timer counter 101, a dead time period register 102, a dead time minimum value register 103, a comparison unit 104, and an error register 105.

[0019] The timer counter 101 counts the timer output by the timer included in the microcomputer 100 to generate a periodic waveform for controlling the motor 300. The dead time period register 102 registers the dead time period TD during which the P-type MOSFET and the N-type MOSFET of the FET circuit 200 are simultaneously OFF, which is calculated at the time of initial setting or at the time of next cycle calculation for calculating various parameters for the operation in the next cycle. The dead time period register 102 registers the dead time period of the FET circuit 200 for each cycle according to the setting in the software execution unit 110.

[0020] The dead time minimum value register 103 is a register that registers the minimum value TDmin of the dead time period TD. The minimum value TDmin is a value at which, if the set dead time period TD falls below this minimum value TDmin, the P-type MOSFET and the N-type MOSFET may simultaneously turn on and a through-current may occur.

[0021] The comparison unit 104 compares the set dead time period TD with the minimum value TDmin to determine whether the former is less than the latter, and outputs a comparison signal as the comparison result. The error register 105 registers an error signal according to the comparison signal and outputs it to the outside. The error register 105 functions as an error signal output circuit that outputs an error signal according to the output of the comparison unit 104.

[0022] Next, the operation of this motor control device 1 will be described with reference to the timing chart of FIG. 2. This timing chart shows the operations of each part, the registered values, and the waveforms of the signals when performing emergency stop processing after the motor 300 stops, during normal operation, and after registering an error signal. In FIG. 2, as the normal operation, only the operation of the last cycle is shown, and the waveforms of the signals in the previous cycles are omitted.

[0023] During the stop of the motor 300, the software execution unit 110 executes initial setting processing for starting the operation of the motor 300, and according to the result of the initial setting calculation, the aforementioned dead time period TD and the dead time minimum value TDmin are set ((1) in FIG. 2).

[0024] When the normal operation of the motor 300 starts according to the initial setting, in order to define one cycle of the operation of the motor 300, the output signal of the timer is counted by the timer counter 101. At the start of one cycle, the timer counter 101 resets the timer count value to zero, then counts up to a predetermined maximum value, and then further counts down. When the count value returns to zero, one cycle ends.

[0025] During the execution of one cycle, the software execution unit 110 calculates various parameters for the operation of the motor 300 in the next cycle. In the next cycle calculation, the dead time period TD in the next cycle is also calculated. For example, the calculation is performed as TD = Tx - 1, and the value is registered in the dead time period register 102. According to TD = Tx - 1 registered in the dead time period register 102, the drive signals u + and u - for conducting the P-type MOSFET and N-type MOSFET of the FET circuit 200 are controlled to have the registered dead time period TD = Tx - 1. Although the illustration is omitted, the same control is performed for the signals v +, v -, w +, w - of other phases.

[0026] Here, if the dead time period TD calculated by the next cycle calculation is greater than or equal to the minimum value TDmin, normal operation continues in the next cycle. On the other hand, if the calculated dead time period TD is, for example, TD = Tx (Figure 2 (2) → (3)), and this value Tx is smaller than the minimum dead time value TDmin = α (Tx < α), the comparison unit 104 detects this and an error signal is registered in the error register 105. The error signal rises from "L" to "H" (Figure 2 (4)), and the software execution unit 110 reads this from the error register 105 and starts emergency stop processing. Once the error signal rises and emergency stop processing begins, the drive signals u+ and u- are stopped thereafter. Although not shown in the diagram, similar control is performed for the signals v+, v-, w+, and w- of the other phases.

[0027] Referring to Figure 3, an example of the configuration of a conventional motor control device 1c will be explained. This motor control device 1c is similarly configured to include a microcomputer (MPC) 100 and an FET circuit (semiconductor circuit) 200 that generates a three-phase drive voltage to drive the motor 300 according to calculations performed by the microcomputer 1, but it only has a dead time period register 102 and does not have a dead time minimum value register 103, a comparison unit 104, or an error register 105.

[0028] Figure 4 is a timing chart illustrating the operation of the motor control device 1c in Figure 3. Similar to the embodiment described above, the dead time period TD is calculated by initial settings and next cycle calculation, and the dead time period in the next cycle is set accordingly by the drive signals u+, u-, etc. Even if this dead time period becomes too small, the operation of the next cycle continues, which can cause the P-type MOSFET and N-type MOSFET of the FET circuit 200 to turn ON simultaneously, potentially leading to the generation of a shoot-through current.

[0029] According to this embodiment, the minimum dead time register 103 sets the minimum value TDmin of the dead time period TD to, for example, α. This is then compared with the dead time period TD. If a dead time period that is too small is set, the comparator 104 and error register 105 execute an error setting, and an emergency stop operation may be initiated. Therefore, according to this embodiment, it is possible to provide a motor control device that can appropriately set the dead time period and suppress the generation of through-current.

[0030] In the example shown in Figure 2, the minimum value TDmin registered in the dead time minimum value register 103 is set to a fixed value α during normal operation, but this is not the only option. For example, the software execution unit 103 can calculate and set an appropriate minimum value TDmin for the next cycle, with a different value for each cycle, and register it in the dead time minimum value register 103.

[0031] The present invention is not limited to the embodiments described above, and includes various modifications. For example, the embodiments described above are described in detail to make the present invention easier to understand, and are not necessarily limited to those having all the configurations described. Furthermore, it is possible to replace parts of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add configurations from other embodiments to the configuration of one embodiment. In addition, it is possible to add, delete, or replace parts of the configuration of each embodiment with other configurations. [Explanation of Symbols]

[0032] 1, 1c... Motor control device 100... Microcontroller 101... Timer counter 102... Dead time period register 102... Dead time period register 103... Dead time minimum register 104...Comparison section 105...Error Register 110...Software execution unit 120...Control signal generation unit 200...FET circuit 300...motor

Claims

1. A timer counter that generates a periodic waveform according to the timer output, An operation setting unit sets the operation defined by the aforementioned periodic waveform for each cycle, A dead time period register registers the dead time period for each cycle according to the settings in the operation setting unit, A dead time minimum value register for registering the minimum value of the aforementioned dead time period, A comparison circuit that compares the dead time period with the minimum value, An error signal output circuit that outputs an error signal according to the output of the comparison circuit. A semiconductor device equipped with a semiconductor device.

2. The semiconductor device according to claim 1, wherein the minimum dead time register registers different minimum values ​​according to the settings in the operation setting unit.

3. The semiconductor device according to claim 1, wherein the operation setting unit sets the operation for each cycle by software processing.

4. The semiconductor device according to any one of claims 1 to 3, wherein the operation setting unit performs a next-cycle calculation during the current cycle to calculate the operation parameters for the next cycle for each cycle.

5. The semiconductor device according to claim 1, which controls an external motor via a semiconductor circuit for motor control.

6. A motor control device that controls a motor via a semiconductor circuit for motor control, A timer counter that generates a periodic waveform for controlling the motor according to the timer output, An operation setting unit sets the operation defined by the aforementioned periodic waveform for each cycle, A dead time period register registers the dead time period of the semiconductor circuit for each cycle, according to the settings in the operation setting unit, A dead time minimum value register for registering the minimum value of the aforementioned dead time period, A comparison circuit that compares the dead time period with the minimum value, An error signal output circuit that outputs an error signal according to the output of the comparison circuit, A motor control device equipped with the following features.

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