CN103715888B - Method for reducing power loss of circuit for driving inductive load - Google Patents
Method for reducing power loss of circuit for driving inductive load Download PDFInfo
- Publication number
- CN103715888B CN103715888B CN201310584935.4A CN201310584935A CN103715888B CN 103715888 B CN103715888 B CN 103715888B CN 201310584935 A CN201310584935 A CN 201310584935A CN 103715888 B CN103715888 B CN 103715888B
- Authority
- CN
- China
- Prior art keywords
- power switch
- inductive load
- switch
- power
- current
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
- 230000001939 inductive effect Effects 0.000 title claims abstract description 61
- 238000000034 method Methods 0.000 title claims abstract description 15
- 230000001965 increasing effect Effects 0.000 claims description 8
- 230000005669 field effect Effects 0.000 claims description 6
- 239000000446 fuel Substances 0.000 claims description 3
- 230000009467 reduction Effects 0.000 claims description 3
- 239000003990 capacitor Substances 0.000 claims description 2
- 238000007599 discharging Methods 0.000 abstract description 2
- 230000004044 response Effects 0.000 description 3
- 230000008901 benefit Effects 0.000 description 2
- 230000001276 controlling effect Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000009471 action Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 230000009977 dual effect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000036039 immunity Effects 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
- 238000004804 winding Methods 0.000 description 1
Images
Landscapes
- Electronic Switches (AREA)
Abstract
A method of reducing power loss in a circuit (100) for driving an inductive load (30) is disclosed. -during a first mode, a current i1 charging the inductive load (30) via a first power switch (10), and-during a freewheel mode, the charged inductive load (30) discharging a current i2 via a second power switch (20), the method characterized by: -detecting an off-state of the first power switch (10); detecting the passage of a first dead time after a switched off state of the first power switch (10); and to turn on the second power switch (20) during the freewheel mode.
Description
Technical Field
The present invention relates to power stage circuits and describes a method for reducing power loss of a power stage circuit driving an inductive load, and in particular to the invention for reducing dead time.
Background
Automotive or industrial applications use motor-controlled subsystems or inductive actuators. Typical examples in automotive applications are motors used to drive cooling fans, pumps, and to move seats, mirrors, or flaps. Modern automobiles typically have between 70 and 100 motors/actuators or inductive loads. A power stage circuit is used to control the operation of an inductive load. These include specialized types of switching circuits that use two switches (high-side and low-side), and one way to implement these switches is to utilize power MOSFET transistors. The high-side switch selectively couples the inductive load to the forward power supply, and the low-side switch selectively couples the inductive load to ground. A Pulse Width Modulation (PWM) control circuit is used to control the high-side and low-side switches. Since the inductive load stores energy, it is important that the stored energy is also selectively depleted. A freewheeling diode is thus coupled in parallel with the inductive load. When the high-side switch is in the on state, current flows through the inductive load and thus the inductive load is charged. When the high-side switch is in an off state, current flows through the freewheeling diode. However, diodes consume more power than MOSFETs. Therefore, the MOSFET preferably performs a freewheeling action. With power MOSFET based switching, it is important to control the dead time of the switches. Dead time refers to the delay between the switching off of the high-side switch to the switching on of the low-side switch or the switching on of the high-side switch to the switching off of the low-side switch. In the known prior art, dead time generators are used to implement the control of the switches. In the known general state of the art, the dead time generator consists of logic gates only, so that the dead time generated is susceptible to manufacturing or temperature. If the dead time is too short, the power switches of the output stage circuit are turned on simultaneously, which generates a large current, causing the power switches to overheat or even break down. If the dead time is too long, the efficiency of the power stage circuit is reduced and the power loss is greatly increased.
The conventional approach adds a constant dead time regardless of operating conditions and equipment tolerances. This reduces efficiency and reduces the maximum switching frequency of the system. Different methods have been proposed to minimize the dead time. The proposed system requires operating conditions and system requirements that cannot be met in a variable speed, drive system. The main differences between a typical motor control system and a conventional system are:
-a varying load current direction.
-no steady state conditions.
An external motor controller, which means that there is no information about the actual duty cycle.
-induced voltages in the motor windings.
Therefore, more effort is required to optimize the dead time of the motor control system.
Disclosure of Invention
Object of the Invention
The object of the present invention is to overcome the drawbacks of the known art in this field. It is another object of the present invention to provide a system and method for operating an inductive load in an efficient manner and thereby reducing power loss of a power stage circuit driving the inductive load. It is another object of the present invention to select an optimum dead time for the switches in the power stage circuit based on the operation of the inductive load so that power losses can be further reduced.
The invention has the advantages of
The invention as claimed in the independent and dependent claims has the following advantageous effects. The invention according to the independent claims provides a system and a method for operating an inductive load. The slew rate of the second power switch is controlled such that the switching time of the second power switch is shortened. Thus, the dead time of the second power switch is reduced, thereby reducing power losses and other electromagnetic interference losses. The dead time of the first power switch and the second power switch is configured to avoid a possible short circuit between the first power switch and the second power switch.
Drawings
Exemplary embodiments of the present invention are generally described below with reference to the accompanying drawings. The drawings are such that,
FIG. 1 shows a block diagram of a circuit according to the present invention;
fig. 2 and 3 show the current versus time characteristics and illustrate the mode of operation of an inductive load; and
fig. 4 illustrates a method of reducing power consumption of a circuit.
Detailed Description
Fig. 1 shows a block diagram of a circuit 100 provided in a vehicle (not shown) for controlling the operation of an inductive load 30, such as a solenoid valve. Solenoid valves are used to control the operation of fuel injectors in fuel injection systems. The circuit 100 includes a first power switch 10 connected in series with an inductive load 30 and a second power switch 20 connected across the inductive load 30. In one configuration, the first power switch 10 may be selectively coupled to a positive terminal of a power source (Ubatt), and the second power switch 20 may be selectively coupled to a reference ground. In a second configuration, the first power switch 10 may be connected to ground and the second power switch 20 may be connected to the positive terminal of the power supply (Ubatt). Any suitable configuration may be devised by those skilled in the art as desired. The switch controller 50 is coupled to the first power switch 10 and the second power switch 20 for controlling the on/off of the first and second power switches to control the operation of the inductive load 30.
The first and second power switches 10, 20 are MOSFET switches with intrinsic body diodes 12, 13 and field effect transistors (transistors) (14, 15), respectively. The shunt element 40 is connected in series with the inductive load 30.
The switch controller 50 is an electronic controller unit integrated with a PWM controller 60, a state machine processor 52, a bootstrap (boot strap) circuit 56 coupled to the high side drive circuit 18 for driving the first power switch 10, and a low side drive circuit 54 coupled to a variable resistive load 70 for driving the second power switch 20. The variable resistive load 70 includes the resistive load Rp connected in series with the switch SW and the combination connected in parallel. The variable resistance R2 is dynamically calculated by closing these switches.
The switch controller 50 is adapted to operate the inductive load 30 in a dual tap current regulation mode to control the average current through the inductive load 30 and to receive current feedback from the shunt resistor 40 via the PWM controller 60 for generating a PWM signal that keeps the current through the inductive load 30 oscillating between predetermined upper and lower threshold values. As shown in fig. 2, the two-point current regulation operation is composed of a "first mode" and a "freewheel mode".
The state machine processor 52 generates on/off requests for the power switches 10, 20 based on the PWM controller signals.
The bootstrap circuit 56 ensures a sufficient gate-source voltage during the on and off states of the first power switch 10.
The high-side drive circuit (18) is designed to ensure that EMC falls within safety limits according to regulatory standards. This means that the circuit is compliant with respect to noise immunity and radiation according to the specifications. This implies that the circuit is designed in such a way that no other circuit can affect its operation (if not desired), or that it cannot affect the state of other circuits (if not desired).
The switch controller 50 is adapted to increase the slew rate of the second power switch 20 such that the time the second power switch 20 is on after the first power switch 10 is off is shortened. The variable resistor R2 in combination with the series resistor R1 may be configured to a desired resistance value, whereby the slew rate of the second power switch may be increased. Further, the resistors R2, R1 and the capacitor C1 are configured to provide a second dead time of the second power switch 20 for safe turn off. The values of R1, R2, and C1 are chosen such that the second dead time is less than the first dead time. The second power switch 20 is turned on after the first power switch 10 is completely turned off and after the first dead time is over, to avoid short-circuiting of the first power switch 10 and the second power switch 20. The first dead time is a safe latency whereby the first power switch 10 is completely off and the second power switch 20 is safely on. The second dead time is a safe latency whereby the second power switch 20 is completely off and safely the first power switch 10 can be turned on.
Slew rate refers to the rate of change of voltage with respect to time. Which is a factor in determining the effective time it takes for a power MOSFET to turn fully on or off.
The first dead time is the time difference between the off command sent to the first power switch 10 and the on command sent to the second power switch (20), and the second dead time is the time difference between the off command sent to the second power switch 20 and the on command sent to the first power switch 10. The second dead time may be shortened by appropriate configuration of the values of R2, R1, and C1, thus effectively increasing the slew rate of the second power switch.
Fig. 2 and 3 show the current and time characteristics and the operation mode of the inductive load 30. In fig. 2, the X-axis shows the time characteristic, and the y-axis shows the current characteristic. The inductive load 30 operates in a first mode and a freewheeling mode. During the first mode, current i1 charges inductive load 30. During the freewheel mode, the current i2 is discharged from the inductive load 30. The rising current i1 shows the charging of the inductive load 30 and the falling current i2 shows the discharging from the inductive load 30. The switch controller 50 controls the operation of the inductive load 30 by turning on/off the first power switch 10 and the second power switch 20. When the first power switch 10 is operated in the on state, the inductive load 30 is charged. The discharge starts when the first power switch 10 is completely turned off. The discharge current i2 flows through the body diode 13 of the second power switch 20 until the second power switch 20 is turned on. If the second power switch 20 is not conducting, the body diode 13 is conducting. The body diode loses more power and thus increases power loss for each freewheel mode of the inductive load 30.
Fig. 3 illustrates reducing power loss of the circuit during the freewheel mode. As shown in fig. 3, the X-axis shows time and the Y-axis shows voltage (volts), current (amps) and power (va) characteristics. As shown, the Y-axis shows the PWM signals for turning on/off the first power switch 10 and the second power switch 20. The signal g _ hsps drives the first power switch 10 via the high-side gate drive circuit 56, and the signal g _ afw drives the second power switch 20 via the low-side gate drive circuit 54. Current IL is the current flowing through inductive load 30 operating in the first mode and the freewheeling mode. The voltage Vgs _ AFW is the voltage across the second power switch 20 when the second power switch 20 is on, and Vgs _ HSBatt is the voltage signal across the first power switch 10 when the first power switch 10 is on. Vds _ AFW is the voltage across the second power switch 20 when the drain current Id _ AFW flows through the second power switch 20. The signal PD _ AFW shows that the power loss flowing through the second power switch 20 is reduced when the transistor 15 of the second power switch 20 is turned on and the first power switch 10 is turned off after the first dead time.
As shown in FIG. 3, when the PWM signal g _ hsps is ON, the first power switch 10 is ON, as shown with 10-ON. The current IL through the inductive load 30 (current i1) increases and reaches a maximum limit. Once the current i1 reaches the upper threshold, the switch controller 50 detects this maximum limit by reading the current flowing through the shunt, and turns off the first power switch 10 by allowing a first dead time for complete turn off. During the first dead time, the second power switch 20 is in a fully off state to avoid a short circuit of the first power switch 10 and the second power switch 20 that would otherwise cause a failure of the switches. Once the first power switch 10 is turned off, the current i2 begins to discharge via the body diode 13 of the second power switch 20. As shown in fig. 3, the power loss PD _ AFW is at a peak. After the first dead time, the switch controller 50 turns on the second power switch 20 by increasing the slew rate. This facilitates conduction via transistor 15. Transistor 15 is turned on quickly and allows current i2 to discharge through the conductive path of transistor 15 of second power switch 20, which reduces power losses as shown in fig. 3. The reduction of the power loss is effective for the period in which the second power switch 20 is fully on. Once the discharge current reaches the lower threshold, the second power switch 20 is off for a second dead time that is less than the first dead time. The switch controller 50 detects the lapse of the second dead time and turns on the first power switch 10. Whenever actuation of the inductive load 30 is required, the switch controller 50 operates the inductive load 30 between the upper and lower limits with two operational limits.
Fig. 4 illustrates a method of reducing power consumption of a circuit. This approach reduces the power loss of the circuit 100 driving the inductive load 30. The method is operated by the switch controller 50. The method detects the operation of the inductive load 30 by measuring the step-up current i1 and the step-down current i2 of the inductive load 30. During the first mode, current i1 flows through the first power switch 10 to charge the inductive load 30, and during the freewheel mode, the charged inductive load 30 discharges current i2 via the second power switch 20. In step S01, the first mode is detected by measuring the elevated current flowing through the inductive load 30 by virtue of the first power switch 10 being turned on. Once the current i1 charges the inductive load 30 and the current i1 reaches the upper limit, the first power switch 10 is turned off. In step S02, since the first power switch 10 requires a safe time for complete turn-off, a first dead time is provided before the second power switch 20 is turned on. In a next step S03, after the first power switch 10 is turned off, the inductive load 30 starts to discharge via the body diode 13 of the second power switch 20 during the freewheel mode of the second power switch 20. The turn-off of the first power switch 10 and the lapse of the first dead time are measured. In the next step S04, the second power switch 20 is turned on by increasing the slew rate, and thus the transistor 15 of the second power switch 20 is turned on quickly, and thus the current i2 starts to flow through the transistor 15 of the second power switch 20. The increase in the slew rate of the second power switch 20 reduces power losses across the body diode 13 of the second power switch 20, since the inductive load 30 discharges current via the transistor 15 instead of the body diode 13. The slew rate of the second power switch 20 is varied by selectively configuring the variable resistive load 70, in combination with the resistor R1. The increase in slew rate results in: the on-time of the second power switch 20 is shortened compared to the on-time of the first power switch 10. The on/off times of the first and second power switches 10, 20 may be controlled based on the PWM signal or current regulation sensed at the shunt element 40. The transition from the freewheel mode to the first mode is achieved by turning off the second power switch 20. Since the slew rate of the second power switch 20 is increased, the conduction is achieved very quickly, and thus the second power switch 20 can be completely turned off in a short time. The second dead time, which is very short compared to the first dead time, elapses before the first power switch 10 is turned on. This ensures that there is no time/very short time for the body diode 12 of the first power switch 10 to conduct.
Due to the increased slew rate and the settings of R2, R1, and C1, the second dead time is now optimized and therefore very short compared to the first dead time. For power stage circuits, longer dead time means longer idle phase, and therefore slower response. Having a reduced dead time provides the benefit of an improved response time of the circuit.
The invention is therefore advantageous for reducing power losses in the second power switch (20). Reducing power losses allows the size of the heat sink required for the second power switch (20) to be reduced. This also means that the housing of the device for dissipating heat can be smaller. Since compact circuits are now possible, which may have a reduced size, less space is consumed on the PCB and, therefore, less cost of the circuit. Furthermore, due to the optimized dead time of the second power switch, this improves the response behavior of the circuit compared to circuits controlled by other power stage MOSFETs.
It should be understood that the embodiments illustrated in the foregoing detailed description are illustrative only and do not limit the scope of the invention. The scope of the invention is limited only by the scope of the claims. Many modifications and variations of the above-described embodiments are contemplated and fall within the scope of the invention.
Claims (11)
1. A method of reducing power loss in a circuit (100) for driving an inductive load (30), wherein during a first mode a current i1 charges the inductive load (30) via a first power switch (10) and during a freewheel mode the charged inductive load (30) releases a current i2 via a second power switch (20), the method characterized by:
-detecting an off-state of the first power switch (10);
-detecting the lapse of a first dead time after the off-state after switching of the first power switch (10); and
-during the freewheel mode, turning on the second power switch (20) and reducing a second dead time for turning off the second power switch (20) with increasing slew rate of the second power switch (20), wherein the slew rate of the second power switch (20) is varied by selectively configuring a variable resistive load (70), a resistor R1 and a capacitor C1.
2. The method according to claim 1, wherein during the freewheel mode, when the second power switch (20) is in a conductive state, the inductive load (30) discharges the current i2 via a field effect transistor (15) of the second power switch (20).
3. A circuit (100) for driving an inductive load (30), the circuit comprising,
-a first power switch (10) connected in series with the inductive load (30);
-a second power switch (20) connected across the inductive load (30);
-a switch controller (50) coupled to the first power switch (10) and the second power switch (20), the switch controller (50) for controlling the on/off times of the first power switch (10) and the second power switch (20) in order to control the operation of the inductive load (30);
-the switch controller (50) is adapted to detect the lapse of a first dead time after a switched off state of the first power switch (10);
-the switch controller (50) is adapted to increase the slew rate of the second power switch (20) thereby enabling a reduction of the on-time of the second power switch (20) after the turn-off of the first power switch (10); and is
-the switch controller (50) is adapted to increase the slew rate of the second power switch (20), thereby enabling a reduction of the off-time of the second power switch (20).
4. A circuit according to claim 3, wherein the first power switch (10) is one MOSFET switch with an intrinsic body diode (12) and a field effect transistor (14), and the second power switch (20) is another MOSFET switch with an intrinsic body diode (13) and a field effect transistor (15).
5. A circuit according to claim 3, wherein, in a first configuration, the first power switch (10) is connected to the positive terminal of a power supply (Ubatt) and the second power switch (20) is connected to ground.
6. A circuit according to claim 3 or 4, wherein the inductive load (30) is charged by a current i1 during the on-time of the first power switch (10), and when the first power switch (10) is switched off, the inductive load (30) discharges a current i2 via the intrinsic body diode (13) of the second power switch (20).
7. A circuit according to claim 3 or 4, wherein the increase in the slew rate of the second power switch (20) enables faster conduction of a field effect transistor (15) of the second power switch (20), and a discharge current i2 flows through the field effect transistor (15) of the second power switch (20) when the first power switch (10) is turned off.
8. The circuit of claim 3 or 4, wherein the increase in the slew rate of the second power switch (20) reduces power losses on an intrinsic body diode (13) of the second power switch (20).
9. A circuit according to claim 3 or 4, wherein the off-time of the second power switch (20) is less than the off-time of the first power switch (10).
10. A circuit according to claim 3, wherein the on/off times of the first and second power switches (10, 20) are controlled on the basis of a time-based PWM signal or a current sensed at a shunt element (40).
11. The circuit of claim 3, wherein the inductive load (30) is a solenoid actuator for actuating a fuel injector.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| IN4069/CHE/2012 | 2012-09-28 | ||
| IN4069CH2012 | 2012-09-28 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN103715888A CN103715888A (en) | 2014-04-09 |
| CN103715888B true CN103715888B (en) | 2020-01-21 |
Family
ID=50408583
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201310584935.4A Expired - Fee Related CN103715888B (en) | 2012-09-28 | 2013-09-27 | Method for reducing power loss of circuit for driving inductive load |
Country Status (2)
| Country | Link |
|---|---|
| CN (1) | CN103715888B (en) |
| BR (1) | BR102013024992B1 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| IN2013CH04874A (en) * | 2013-10-29 | 2015-05-08 | Robert Bosch Eng & Business Solutions Ltd | |
| US11146260B1 (en) * | 2020-07-28 | 2021-10-12 | Hygon Information Technology Co., Ltd. | Circuit and method to manage and recover from bias temperature instability |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1819461A (en) * | 2006-03-06 | 2006-08-16 | 中南大学 | Dead zone protecting circuit of electronic prospecting signal transmitter |
| CN101309529A (en) * | 2008-06-27 | 2008-11-19 | 武汉理工大学 | Intelligent control apparatus and method for high-power energy saving electromagnetic stove |
| CN101778520A (en) * | 2010-01-08 | 2010-07-14 | 福州大学 | Method for controlling soft switching of zero voltage quasi-square wave BUCK transducer and circuit thereof |
| CN101783582A (en) * | 2010-02-26 | 2010-07-21 | 东南大学 | Single-input dual-output pulse-width modulation signal generating circuit with adjustable dead time |
-
2013
- 2013-09-27 CN CN201310584935.4A patent/CN103715888B/en not_active Expired - Fee Related
- 2013-09-27 BR BR102013024992-0A patent/BR102013024992B1/en active IP Right Grant
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1819461A (en) * | 2006-03-06 | 2006-08-16 | 中南大学 | Dead zone protecting circuit of electronic prospecting signal transmitter |
| CN101309529A (en) * | 2008-06-27 | 2008-11-19 | 武汉理工大学 | Intelligent control apparatus and method for high-power energy saving electromagnetic stove |
| CN101778520A (en) * | 2010-01-08 | 2010-07-14 | 福州大学 | Method for controlling soft switching of zero voltage quasi-square wave BUCK transducer and circuit thereof |
| CN101783582A (en) * | 2010-02-26 | 2010-07-21 | 东南大学 | Single-input dual-output pulse-width modulation signal generating circuit with adjustable dead time |
Also Published As
| Publication number | Publication date |
|---|---|
| BR102013024992A2 (en) | 2015-12-22 |
| BR102013024992B1 (en) | 2021-10-05 |
| CN103715888A (en) | 2014-04-09 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US9825617B2 (en) | Inductive load driver slew rate controller | |
| JP4359855B2 (en) | Solenoid valve drive circuit and solenoid valve | |
| JP4431996B2 (en) | Solenoid valve drive circuit and solenoid valve | |
| US9602097B2 (en) | System and method having a first and a second operating mode for driving an electronic switch | |
| CN106357251B (en) | Semiconductor switch device | |
| US8497714B2 (en) | System and method for driving a switch transistor | |
| US10217734B2 (en) | Semiconductor device | |
| EP3205006A1 (en) | Pulsed linear power converter | |
| WO2002063770A2 (en) | Switching fet circuit | |
| CN104617933B (en) | Circuit for reducing power consumption of power stage and method thereof | |
| JP2010054054A (en) | Solenoid valve driving circuit and solenoid valve | |
| JP4753729B2 (en) | Switching control circuit | |
| JP2008067593A (en) | Gate drive circuit for insulated gate semiconductor switching elements | |
| CN103715888B (en) | Method for reducing power loss of circuit for driving inductive load | |
| JP6767328B2 (en) | Solenoid drive circuit | |
| CN110635794B (en) | Rectifier circuit, switching power converter using same and related methods | |
| CN112840565B (en) | Control method of DC-DC voltage converter | |
| US8638129B2 (en) | Power circuit | |
| JP5450248B2 (en) | Electronic control unit | |
| KR20040068853A (en) | Actuator Driving Apparatus and Method | |
| CN118353337A (en) | Gate drive with phase slew rate control and over-current protection | |
| JP6527788B2 (en) | Electromagnetic load drive | |
| CN113054836A (en) | Direct current conversion circuit | |
| CN116722717A (en) | Minimum peak current of power converter | |
| JP2015130553A (en) | inductive load drive device |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20200121 Termination date: 20210927 |
|
| CF01 | Termination of patent right due to non-payment of annual fee |