JP7012225B2 - Heating device and relay switching control method - Google Patents

Description

The present disclosure relates to a heating device, and more particularly to a switching control method for an electromagnetic relay (hereinafter, simply referred to as a relay) used in the heating device.

In a heating device, a relay is used to control on / off of a heater or the like. A relatively large current is supplied to the relay coil to drive the relay. Therefore, if the relay is switched frequently, the amount of heat generated becomes large.

For the above reasons, the relay for controlling the on / off of the heat source of the heating device is required to reduce the amount of heat generated and to reliably perform the switching operation. Various relay drive circuits have been developed to meet such demands (see, for example, Patent Documents 1 and 2).

Japanese Unexamined Patent Publication No. 03-134928 Japanese Unexamined Patent Publication No. 08-266800

In the above-mentioned conventional heating device, at the time of starting, a moving current for setting the relay in the set state (operating state) is supplied to the relay coil, and after the bounce time elapses, a holding current smaller than the moving current is supplied to the relay coil. , Holds the set state of the relay. As a result, the amount of heat generated is reduced.

In the above-mentioned conventional heating device, sound is generated from the relay contact every time the relay is driven. Hereinafter, this sound is referred to as an operation sound of the relay contact, or simply an operation sound. In the case of a heating device in which multiple relays are frequently turned on / off, there is a constant operating noise of the relay contacts.

The present disclosure aims at reducing the operating noise of relay contacts in addition to reliable switching operation and reduction of heat generation amount in a relay used in a heating device.

The heating device of one aspect of the present disclosure includes a passive element, a relay, a relay drive unit, and a control unit. The relay is connected in series with the passive element. The relay drive unit supplies the relay with a moving current for shifting the relay to the set state and a current smaller than the moving current. The control unit drives the relay to supply a current smaller than the moving current to the relay before shifting the relay to the set state, and then to supply a further moving current to the relay while supplying a current smaller than the moving current. It is configured to control the unit to control the relay drive unit that shifts the relay to the set state .

According to this aspect, in the relay used in the heating device, it is possible to reduce the operating noise of the relay contact in addition to the reliable switching operation and the reduction of the heat generation amount.

FIG. 1 is a circuit block diagram of an induction heating cooker according to the first embodiment of the present disclosure. FIG. 2 is a functional block diagram of the induction heating cooker according to the first embodiment. FIG. 3 is a circuit block diagram showing a specific configuration of the relay drive unit according to the first embodiment. FIG. 4 is a timing chart showing a relay switching control method for setting a relay in a comparative example. FIG. 5 is a timing chart showing a relay switching control method for setting a relay in the first embodiment. FIG. 6 is a timing chart showing a relay switching control method for resetting the relay in the comparative example. FIG. 7 is a timing chart showing a relay switching control method for resetting the relay in the first embodiment. FIG. 8 is a circuit block diagram of the cooking device according to the second embodiment of the present disclosure.

The heating device of the first aspect of the present disclosure includes a passive element, a relay, a relay drive unit, and a control unit. The relay is connected in series with the passive element. The relay drive unit supplies the relay with a moving current for shifting the relay to the set state and a current smaller than the moving current. The control unit is configured to control the relay drive unit so as to supply the relay with a current smaller than the moving current before shifting the relay to the set state.

According to the heating device of the second aspect of the present disclosure, in the first aspect, the relay drive unit is a moving current generation circuit configured to supply a moving current to the relay, and a current smaller than the moving current. Includes a holding current generation circuit configured to supply the relay with holding current to keep the relay set.

The control unit is configured to control the holding current generation circuit so as to supply the holding current, and to control the moving current generation circuit so as to stop the moving current after supplying the moving current.

According to the heating device of the third aspect of the present disclosure, in the second aspect, the relay drive unit has a current smaller than the holding current and supplies an open current for shifting the relay to the reset state to the relay. Further includes a current generation circuit.

The control unit controls the open current generation circuit so as to generate an open current, controls the hold current generation circuit so as to stop the holding current, and controls the open current generation circuit so as to stop the open current. It is composed.

According to the relay switching control method of the fourth aspect of the present disclosure, before shifting the relay to the set state, a current smaller than the moving current for shifting the relay to the set state is supplied to the relay.

According to the relay switching control method of the fifth aspect of the present disclosure, in the fourth aspect, the current is smaller than the moving current, the holding current for maintaining the relay in the set state is supplied, and the moving current is supplied. , After shifting the relay to the set state, stop the moving current.

According to the relay switching control method of the sixth aspect of the present disclosure, in the fifth aspect, a current smaller than the holding current, an open current for shifting the relay to the reset state is supplied, and the holding current is stopped. After shifting the relay to the reset state, the open current is stopped.

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

Each embodiment is a specific example of the present disclosure. The numerical values, shapes, configurations, and the like shown in the embodiments are examples, and do not limit the present disclosure.

(Embodiment 1)
The first embodiment is an example in which the relay switching control method according to the present disclosure is applied to an induction heating cooker which is a heating device.

FIG. 1 is a circuit block diagram of an induction heating cooker according to the present embodiment.

As shown in FIG. 1, the induction heating cooker of the present embodiment has a drive unit 2, a heating coil 3a, 3b, a switching unit 4, a control unit 10, and a relay drive unit 19 inside a main body (not shown). And have.

The heating coils 3a and 3b, which are passive elements, are provided in close proximity to a top plate (not shown) that covers the upper part of the main body. The heating coils 3a and 3b are connected in parallel. The top plate is provided with an operation display unit 20 configured to set heating conditions and start heating by the user and to display the set heating conditions and operating status.

As shown in FIGS. 1 and 2, the switching unit 4 includes relays 4a and 4b connected in series to the heating coils 3a and 3b, respectively. The relay 4a connects or disconnects the electric circuit between the heating coil 3a and the drive unit 2. The relay 4b connects or disconnects the electric circuit between the heating coil 3b and the drive unit 2. The relays 4a and 4b are composed of mechanical or semiconductor type relays.

The relay drive unit 19 includes relay drive circuits 17 and 18. The relay drive circuit 17 is controlled by the drive control unit 11 and is configured to drive the relay 4a. The relay drive circuit 18 is controlled by the drive control unit 11 and is configured to drive the relay 4b.

The drive unit 2 generates a high-frequency current from the electric power supplied by the commercial power source 1, and supplies the high-frequency current to the heating coils 3a and 3b via the relays 4a and 4b.

The drive unit 2 includes a diode bridge 5, a smoothing circuit 8, an inverter 9, a snubber capacitor 16, resonance capacitors 15a and 15b, an input current detector 13, and an output current detector 14.

The diode bridge 5 rectifies the AC power of the commercial power source 1 and outputs DC power. The smoothing circuit 8 has a choke coil 6 and a smoothing capacitor 7, and smoothes the rectified DC power.

The inverter 9 is configured by connecting a switching element 9a arranged on the high voltage side and a switching element 9b arranged on the low voltage side in series. For the switching elements 9a and 9b, for example, an IGBT is used. A reverse conduction diode is connected in parallel to each of the switching elements 9a and 9b. The inverter 9 is connected to both ends of the smoothing capacitor 7. The drive control unit 11 controls the switching elements 9a and 9b.

The resonance capacitor 15a is connected in series to the heating coil 3a and constitutes a resonance circuit together with the heating coil 3a. The resonance capacitor 15b is connected in series with the heating coil 3b and constitutes a resonance circuit together with the heating coil 3b.

The snubber capacitor 16 reduces the switching loss that occurs when the switching elements 9a and 9b are turned off. The snubber capacitor 16 is connected in parallel to the switching element 9b.

The input current detector 13 is provided between the commercial power supply 1 and the diode bridge 5, and detects the input current supplied to the diode bridge 5. The output current detector 14 is provided between the connection points of the switching elements 9a and 9b and the heating coils 3a and 3b, and detects the output current flowing through the inverter 9.

The load detection unit 12 determines whether or not a load is placed above the heating coils 3a and 3b based on the detected input current and output current. The drive control unit 11 controls the drive unit 2 according to the determination. The load detection unit 12 and the drive control unit 11 constitute the control unit 10.

In the present embodiment, the microcomputer constitutes the control unit 10. The present disclosure is not limited to this, but if a programmable microcomputer is used, the processing content can be easily changed and the degree of freedom in design can be increased.

In order to improve the processing speed, it is also possible to configure the control unit 10 with a logic circuit. The control unit 10 may be physically composed of one or a plurality of electronic components. When the control unit 10 is composed of a plurality of electronic components, each element included in the control unit 10 may be associated with one electronic component. In that case, it can be considered that these electronic components correspond to the drive control unit 11 and the load detection unit 12.

[Load detection]
The induction heating cooker of the present embodiment has a first heating region provided on the top plate above the heating coil 3a and a second heating region provided on the top plate above the heating coil 3b. ..

Whether or not a load such as a pan is placed in the first heating region of the load detection unit 12 with the drive control unit 11 in the set state (operating state) and the relay 4b in the reset state (reset state). Is detected based on the detected changes in the input current and the output current.

Next, the drive control unit 11 sets the relay 4a in the reset state, the relay 4b is in the set state, and the load detection unit 12 determines whether or not the load is placed in the second heating region, and the detected input current. And detect based on changes in output current.

By this series of operations (hereinafter referred to as load detection), the load detection unit 12 detects whether or not a load is placed in the first heating region and the second heating region.

After starting the induction cooker, the control unit 10 frequently performs load detection. Specifically, for load detection, switching of relays 4a and 4b is repeated at predetermined time intervals, for example, between 1.2 and 2.0 seconds. Therefore, reducing the operating noise generated when the relays 4a and 4b are switched is an important issue.

In the present embodiment, the operating noise of the relay contacts is reduced by the relay switching control method described below.

[Relay switching control method]
FIG. 2 is a functional block diagram of the induction heating cooker according to the present embodiment.

As shown in FIG. 2, the relay drive circuit 17 has a holding current generation circuit 17a, a moving current generation circuit 17b, and an open current generation circuit 17c, and drives the relay 4a. The relay drive circuit 18 has a holding current generation circuit 18a, a moving current generation circuit 18b, and an open current generation circuit 18c, and drives the relay 4b.

The holding current generation circuit 17a generates the holding current S1 in response to the control signal output by the drive control unit 11. The holding current generation circuit 17a supplies the holding current S1 to the relay 4a so as to keep the relay 4a in the set state.

The moving current generation circuit 17b generates a moving current S2 in response to a control signal output by the drive control unit 11. The moving current generation circuit 17b supplies the moving current S2 to the relay 4a so as to shift the relay 4a in the reset state to the set state.

The open current generation circuit 17c generates an open current S3 in response to a control signal output by the drive control unit 11. The open current generation circuit 17c supplies the open current S3 to the relay 4a so as to shift the relay 4a from the set state to the reset state.

The holding current generation circuit 18a generates the holding current S1 in response to the control signal output by the drive control unit 11. The holding current generation circuit 18a supplies the holding current S1 to the relay 4b so as to keep the relay 4b in the set state.

The moving current generation circuit 18b generates a moving current S2 in response to a control signal output by the drive control unit 11. The moving current generation circuit 18b supplies the moving current S2 to the relay 4b so as to shift the relay 4b in the reset state to the set state.

The open current generation circuit 18c generates an open current S3 in response to a control signal output by the drive control unit 11. The open current generation circuit 18c supplies the open current S3 to the relay 4b so as to shift the relay 4b from the set state to the reset state.

As described above, the moving current S2 is supplied in order to shift the relay 4a in the reset state to the set state. Needless to say, when a current of the moving current S2 or more is supplied, the relay 4a shifts to the set state.

FIG. 3 is a circuit block diagram showing a specific configuration of the relay drive unit 19 according to the present embodiment.

As shown in FIG. 3, the relay drive unit 19 further includes DC power supply circuits 23a and 23b. The relay 4a includes a relay contact 21a and a relay coil 22a. The relay 4b includes a relay contact 21b and a relay coil 22b.

The relay coil 22a is provided in the electric circuit between the DC power supply circuit 23a and the relay drive circuit 17. The relay coil 22b is provided in the electric circuit between the DC power supply circuit 23b and the relay drive circuit 18.

The holding current generation circuit 17a, the moving current generation circuit 17b, and the open current generation circuit 17c are connected in parallel.

The holding current generation circuit 17a has a transistor 24a and a resistor 25a. When the transistor 24a is turned on in response to the control signal output by the drive control unit 11, the holding current S1 corresponding to the resistor 25a is supplied from the DC power supply circuit 23a to the relay coil 22a.

The moving current generation circuit 17b has a transistor 26a and a resistor 27a. When the transistor 26a is turned on in response to the control signal output by the drive control unit 11, the moving current S2 corresponding to the resistor 27a is supplied from the DC power supply circuit 23a to the relay coil 22a.

The open current generation circuit 17c has a transistor 28a and a resistor 29a. When the transistor 28a is turned on in response to the control signal output by the drive control unit 11, the open current S3 corresponding to the resistor 29a is supplied from the DC power supply circuit 23a to the relay coil 22a.

The force applied to the relay contact 21a by the moving current S2 is larger than the force applied to the relay contact 21a by the holding current S1. The force applied to the relay contact 21a by the holding current S1 is larger than the force applied to the relay contact 21a by the opening current S3.

The holding current generation circuit 18a, the moving current generation circuit 18b, and the open current generation circuit 18c are connected in parallel.

The holding current generation circuit 18a has a transistor 24b and a resistor 25b. When the transistor 24b is turned on in response to the control signal output by the drive control unit 11, the holding current S1 corresponding to the resistor 25b is supplied from the DC power supply circuit 23b to the relay coil 22b.

The moving current generation circuit 18b has a transistor 26b and a resistor 27b. When the transistor 26b is turned on in response to the control signal output by the drive control unit 11, the moving current S2 corresponding to the resistor 27b is supplied from the DC power supply circuit 23b to the relay coil 22b.

The open current generation circuit 18c has a transistor 28b and a resistor 29b. When the transistor 28b is turned on in response to the control signal output by the drive control unit 11, the open current S3 corresponding to the resistor 29b is supplied from the DC power supply circuit 23b to the relay coil 22b.

The force applied to the relay contact 21b by the moving current S2 is larger than the force applied to the relay contact 21b by the holding current S1. The force applied to the relay contact 21b by the holding current S1 is larger than the force applied to the relay contact 21b by the opening current S3.

Hereinafter, the relay switching control method according to the present embodiment will be described using a timing chart. Here, a relay switching control method for the relay 4a will be described. Since the relay switching control method for the relay 4b is the same as that for the relay 4a, the description thereof will be omitted.

First, a relay switching control method for shifting the relay 4a from the reset state to the set state will be described.

FIG. 4 shows a relay switching control method for setting the relay 4a in the prior art which is a comparative example. The waveform (a) of FIG. 4 shows the operation of the transistors 24a and 26a, and the waveform (b) of FIG. 4 shows the current flowing through the relay coil 22a.

As shown in the waveforms (a) and (b) of FIG. 4, in this comparative example, the transistors 24a and 26a are turned on at the same time in order to set the relay 4a. As a result, the holding current S1 and the moving current S2 start to be supplied to the relay coil 22a at the same time.

After that, when a predetermined time (for example, 100 ms) in consideration of the operation time, bounce time, and the like in the relay 4a elapses, the transistor 26a is turned off. As a result, only the holding current S1 is supplied to the relay coil 22a, and the set state of the relay 4a is maintained.

According to this comparative example, the supply of the holding current S1 and the moving current S2 is started at the same time, and the current exceeding the moving current S2 is supplied at once. Therefore, the relay coil 22a is abruptly excited, and the relay contact 21a is driven with a strong force. As a result, a loud operating noise is generated when the relay 4a is set.

In order to reduce the operating noise generated when the relay 4a is set, the induction heating cooker according to the present embodiment performs the following relay switching control method.

FIG. 5 shows a relay switching control method for shifting the relay 4a from the reset state to the set state in the present embodiment. The waveform (a) of FIG. 5 shows the operation of the transistors 24a and 26a, and the waveform (b) of FIG. 5 shows the current flowing through the relay coil 22a.

As shown in the waveforms (a) and (b) of FIG. 5, in the present embodiment, the transistor 24a is first turned on in order to set the relay 4a. After that, when Ton1 elapses for a predetermined time, the transistor 26a is turned on. The predetermined time Ton1 corresponds to the first on time and is set to a time in the range of 10 to 40 ms, for example, 20 ms.

In the present embodiment, a current smaller than the moving current S2 (for example, holding current S1) is once supplied to excite the relay coil 22a. Since the current in this case is smaller than the moving current S2, the relay 4a does not shift to the set state at this timing.

After the elapse of Ton1 for a predetermined time, the relay 4a shifts to the set state only when a current of the moving current S2 or more is supplied. According to the present embodiment, by exciting the relay coil 22a with a current smaller than the moving current S2 before supplying the moving current S2, it is possible to reduce the operating noise generated when the relay 4a is set.

After that, when the predetermined time Ton2 in consideration of the operation time, the bounce time, and the like in the relay 4a elapses, the transistor 26a is turned off. As a result, only the holding current S1 is supplied to the relay coil 22a, and the set state of the relay 4a is maintained. The predetermined time Ton2 corresponds to the second on time and is set to a time in the range of 10 to 80 ms, for example, 40 ms. By the relay switching control method, the relay 4a surely shifts to the set state.

In the comparative example shown in FIG. 4, the predetermined time from when the transistor 26a is turned on to when the transistor 26a is turned off is set to 100 ms. In the present embodiment, the predetermined time Ton2 from when the transistor 26a is turned on to when the transistor 26a is turned off is set to 40 ms.

In the present embodiment, since the relay contact 21a operates more slowly than in the comparative example, the state of the relay 4a stabilizes faster. Therefore, the supply period of the moving current S2 can be shortened. As a result, it is possible to reduce the amount of heat generated in addition to reducing the operating noise.

Next, a relay switching control method for shifting the relay 4a from the set state to the reset state will be described.

FIG. 6 shows a relay switching control method for resetting the relay 4a in the prior art which is a comparative example. The waveform (a) of FIG. 6 shows the operation of the transistor 24a, and the waveform (b) of FIG. 6 shows the current flowing through the relay coil 22a.

As shown in the waveforms (a) and (b) of FIG. 6, in this comparative example, in order to reset the relay 4a, the transistor 24a is turned off and the supply of the holding current S1 to the relay coil 22a is stopped. When the current supplied to the relay coil 22a becomes the open current S3 or less, the relay 4a shifts to the reset state.

According to this comparative example, when the supply of the holding current S1 is stopped, the current flowing through the relay coil 22a sharply decreases. Therefore, the force acting on the relay contact 21a is sharply reduced. As a result, a loud operating noise is generated when the relay 4a is reset.

In order to reduce the operating noise generated when the relay 4a is reset, the induction heating cooker according to the present embodiment performs the following relay switching control method.

FIG. 7 shows a relay switching control method for shifting the relay 4a from the set state to the reset state in the present embodiment. The waveform (a) of FIG. 7 shows the operation of the transistors 24a and 28a, and the waveform (b) of FIG. 7 shows the current flowing through the relay coil 22a.

As shown in the waveforms (a) and (b) of FIG. 7, when the relay 4a is in the set state, the transistor 24a is turned on and the holding current S1 is supplied to the relay coil 22a.

In this embodiment, the transistor 28a is first turned on in order to reset the relay 4a. After that, when Toff1 elapses for a predetermined time, the transistor 24a is turned off. The predetermined time Toff1 corresponds to the first off time and is set to a time in the range of 10 to 500 ms, for example, 200 ms.

After that, when Toff2 elapses for a predetermined time, the transistor 28a is turned off. The predetermined time Toff2 corresponds to the second off time and is set to a time in the range of 10 to 100 ms, for example, 50 ms. By the relay switching control method, the relay 4a surely shifts to the reset state.

In the present embodiment, the open current S3 is temporarily added while the holding current S1 is being supplied. Since the current in this case is larger than the holding current S1, the relay 4a remains in the set state.

When the supply of the holding current S1 is stopped after the lapse of the predetermined time Turn 1, the current supplied to the relay coil 22a drops to the open current S3, and the relay 4a shifts to the reset state. At this time, that is, after a predetermined time has elapsed from the stop of the supply of the holding current S1, the supply of the open current S3 is stopped.

In the present embodiment, the current supplied to the relay coil 22a is changed from the holding current S1 to the open current S3, and then the current to the relay coil 22a is stopped. As a result, the relay contact 21a operates more slowly than in the comparative example. As a result, it is possible to reduce the operating noise generated when the relay 4a is reset.

As described above, according to the present embodiment, in the relay used in the heating device, it is possible to reduce the operating noise of the relay contact in addition to the reliable switching operation and the reduction of the heat generation amount.

(Embodiment 2)
The second embodiment is an example in which the relay switching control method according to the present disclosure is applied to a roaster which is a heating device.

FIG. 8 is a circuit block diagram of a roaster according to the present embodiment. The roaster according to the present embodiment is a cooking cooker having two heaters (heaters 30a and 30b) provided in the upper part and the lower part in a heating chamber (not shown).

As shown in FIG. 8, the heaters 30a and 30b are composed of resistors which are passive elements and are connected in parallel. Electric power from the commercial power source 1 is supplied to the heaters 30a and 30b.

The roaster according to the present embodiment further includes a switching unit 4 (relays 4a and 4b) and a relay driving unit 19. The relay drive unit 19 includes DC power supply circuits 23a and 23b in addition to the relay drive circuits 17 and 18. The relay 4a is connected in series with the heater 30a, and the relay 4b is connected in series with the heater 30b.

The configuration for driving the relays 4a and 4b and the relay switching control method are the same as those in the first embodiment, and the description thereof will be omitted.

As described above, according to the present embodiment, in the relay used in the heating device, it is possible to reduce the operating noise of the relay contact in addition to the reliable switching operation and the reduction of the heat generation amount.

As described above, the present disclosure can be applied to a heating device.

1 Commercial power supply 2 Drive unit 3a, 3b Heating coil 4a, 4b Relay 5 Diode bridge 6 Choke coil 7 Smoothing capacitor 8 Smoothing circuit 9 Inverter 9a, 9b Switching element 10 Control unit 11 Drive control unit 12 Load detector 13 Input current detector 14 Output current detector 15a, 15b Resonant capacitor 16 Snubber capacitor 17,18 Relay drive circuit 17a, 18a Holding current generation circuit 17b, 18b Impressive current generation circuit 17c, 18c Open current generation circuit 19 Relay drive unit 20 Operation display unit 21a, 21b Relay contact 22a, 22b Relay coil 23a, 23b DC power supply circuit 24a, 24b, 26a, 26b, 28a, 28b Transistor 25a, 25b, 27a, 27b, 29a, 29b Resistor

Claims (5)

Passive elements and
A relay connected in series with the passive element,
A relay drive unit configured to supply a moving current for shifting the relay to the set state and a current smaller than the moving current to the relay.
A control unit configured to control the relay drive unit is provided.
Before shifting the relay to the set state, the control unit supplies the relay with a current smaller than the moving current, and then further supplies the moving current in a state where the current smaller than the moving current is supplied. A heating device configured to control the relay drive unit so as to supply the relay and shift the relay to the set state. The relay drive unit has a moving current generation circuit configured to supply the moving current to the relay, and a holding current that is smaller than the moving current and for maintaining the relay in the set state. Includes a holding current generation circuit configured to supply the relay.
The control unit is configured to control the holding current generation circuit so as to supply the holding current, and after supplying the moving current, control the moving current generation circuit so as to stop the moving current. The heating device according to claim 1. The relay drive unit further includes an open current generation circuit in which the current is smaller than the holding current and the open current for shifting the relay to the reset state is supplied to the relay.
The control unit controls the open current generation circuit so as to generate the open current, controls the hold current generation circuit so as to stop the holding current, and the open current so as to stop the open current. The heating device according to claim 2, which is configured to control a generation circuit. A relay switching control method in which a control unit controls a relay drive unit configured to supply a current to a relay to switch the operation of the relay.
Before shifting the relay to the set state , the control unit supplies the relay with a current smaller than the moving current for shifting the relay to the set state, and then supplies the current smaller than the moving current. A relay switching control method in which the relay drive unit is controlled so as to further supply the moving current to the relay in this state, and the relay is shifted to the set state. The control unit controls the relay drive unit to supply a holding current which is smaller than the moving current and for maintaining the relay in the set state, and supplies the moving current to the relay. The relay switching control method according to claim 4, wherein the moving current is stopped after shifting to the set state.

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